Metadata-Version: 2.1
Name: substrate-interface
Version: 1.2.8
Summary: Library for interfacing with a Substrate node
Home-page: https://github.com/polkascan/py-substrate-interface
Author: Stichting Polkascan (Polkascan Foundation)
Author-email: info@polkascan.org
License: UNKNOWN
Description: # Python Substrate Interface
        
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        Python Substrate Interface Library
        
        ## Description
        This library specializes in interfacing with a Substrate node, providing additional convenience methods to deal with
        SCALE encoding/decoding (the default output and input format of the Substrate JSONRPC), metadata parsing, type registry
        management and versioning of types.
        
        ## Table of Contents
        
        * [Documentation](#documentation)
        * [Installation](#installation)
        * [Initialization](#initialization)
          * [Autodiscover mode](#autodiscover-mode)
          * [Manually set required properties](#manually-set-required-properties)  
          * [Substrate Node Template](#substrate-node-template)
        * [Features](#features)
          * [Get extrinsics for a certain block](#retrieve-extrinsics-for-a-certain-block)
          * [Subscribe to new block headers](#subscribe-to-new-block-headers)
          * [Storage queries](#storage-queries)
          * [Storage subscriptions](#storage-subscriptions)
          * [Query a mapped storage function](#query-a-mapped-storage-function)
          * [Create and send signed extrinsics](#create-and-send-signed-extrinsics)
          * [Examining the ExtrinsicReceipt object](#examining-the-extrinsicreceipt-object)
          * [ink! contract interfacing](#ink-contract-interfacing)
          * [Create mortal extrinsics](#create-mortal-extrinsics)
          * [Keypair creation and signing](#keypair-creation-and-signing)
          * [Creating keypairs with soft and hard key derivation paths](#creating-keypairs-with-soft-and-hard-key-derivation-paths)
          * [Creating ECDSA keypairs with BIP44 derivation paths](#creating-ecdsa-keypairs-with-bip44-derivation-paths)
          * [Verify generated signature with public address](#verify-generated-signature-with-public-address)
          * [Getting estimate of network fees for extrinsic in advance](#getting-estimate-of-network-fees-for-extrinsic-in-advance)
          * [Offline signing of extrinsics](#offline-signing-of-extrinsics)
          * [Accessing runtime constants](#accessing-runtime-constants)
        * [Keeping type registry presets up to date](#keeping-type-registry-presets-up-to-date)
        * [Cleanup and context manager](#cleanup-and-context-manager)  
        * [Contact and Support](#contact-and-support)
        * [License](#license)
        
        ## Documentation
        https://polkascan.github.io/py-substrate-interface/
        
        ## Installation
        ```bash
        pip install substrate-interface
        ```
        
        ## Initialization
        
        The following examples show how to initialize for supported chains:
        
        ### Autodiscover mode
        
        ```python
        substrate = SubstrateInterface(
            url="wss://rpc.polkadot.io"
        )
        ```
        
        When only an `url` is provided, it tries to determine certain properties like `ss58_format` and 
        `type_registry_preset` automatically by calling the RPC method `system_properties`. 
        
        At the moment this will work for most `MetadataV14` and above chains like Polkadot, Kusama, Acala, Moonbeam, for other 
        chains the `ss58_format` (default 42) and  `type_registry` (defaults to the latest vanilla Substrate types) should be 
        set manually. 
        
        ### Manually set required properties
        
        Polkadot
        
        ```python
        substrate = SubstrateInterface(
            url="wss://rpc.polkadot.io",
            ss58_format=0,
            type_registry_preset='polkadot'
        )
        ```
        
        Kusama
        
        ```python
        substrate = SubstrateInterface(
            url="wss://kusama-rpc.polkadot.io/",
            ss58_format=2,
            type_registry_preset='kusama'
        )
        ```
        
        Rococo
        
        ```python
        substrate = SubstrateInterface(
            url="wss://rococo-rpc.polkadot.io",
            ss58_format=42,
            type_registry_preset='rococo'
        )
        ```
        
        Westend
        
        ```python
        substrate = SubstrateInterface(
            url="wss://westend-rpc.polkadot.io",
            ss58_format=42,
            type_registry_preset='westend'
        )
        ```
        
        ### Substrate Node Template
        Compatible with https://github.com/substrate-developer-hub/substrate-node-template 
        
        ```python
        substrate = SubstrateInterface(
            url="ws://127.0.0.1:9944",
            ss58_format=42,
            type_registry_preset='substrate-node-template'
        )
         
        ```
        
        ## Features
        
        ### Retrieve extrinsics for a certain block 
        
        #### Method 1: access serialized value
        
        ```python
        # Set block_hash to None for chaintip
        block_hash = "0x51d15792ff3c5ee9c6b24ddccd95b377d5cccc759b8e76e5de9250cf58225087"
        
        # Retrieve extrinsics in block
        result = substrate.get_block(block_hash=block_hash)
        
        for extrinsic in result['extrinsics']:
        
            if 'address' in extrinsic.value:
                signed_by_address = extrinsic.value['address']
            else:
                signed_by_address = None
        
            print('\nPallet: {}\nCall: {}\nSigned by: {}'.format(
                extrinsic.value["call"]["call_module"],
                extrinsic.value["call"]["call_function"],
                signed_by_address
            ))
        
            # Loop through call params
            for param in extrinsic.value["call"]['call_args']:
        
                if param['type'] == 'Balance':
                    param['value'] = '{} {}'.format(param['value'] / 10 ** substrate.token_decimals, substrate.token_symbol)
        
                print("Param '{}': {}".format(param['name'], param['value']))
        ```
        
        #### Method 2: access nested objects
        
        ```python
        # Set block_hash to None for chaintip
        block_hash = "0x51d15792ff3c5ee9c6b24ddccd95b377d5cccc759b8e76e5de9250cf58225087"
        
        # Retrieve extrinsics in block
        result = substrate.get_block(block_hash=block_hash)
        
        for extrinsic in result['extrinsics']:
        
            if 'address' in extrinsic:
                signed_by_address = extrinsic['address'].value
            else:
                signed_by_address = None
        
            print('\nPallet: {}\nCall: {}\nSigned by: {}'.format(
                extrinsic["call"]["call_module"].name,
                extrinsic["call"]["call_function"].name,
                signed_by_address
            ))
        
            # Loop through call params
            for param in extrinsic["call"]['call_args']:
        
                if param['type'] == 'Balance':
                    param['value'] = '{} {}'.format(param['value'] / 10 ** substrate.token_decimals, substrate.token_symbol)
        
                print("Param '{}': {}".format(param['name'], param['value']))
        ```
        
        ### Subscribe to new block headers
        
        ```python
        def subscription_handler(obj, update_nr, subscription_id):
        
            print(f"New block #{obj['header']['number']} produced by {obj['author']}")
        
            if update_nr > 10:
                return {'message': 'Subscription will cancel when a value is returned', 'updates_processed': update_nr}
        
        
        result = substrate.subscribe_block_headers(subscription_handler, include_author=True)
        ```
        
        ### Storage queries
        The modules and storage functions are provided in the metadata (see `substrate.get_metadata_storage_functions()`),
        parameters will be automatically converted to SCALE-bytes (also including decoding of SS58 addresses).
        
        #### Example 
        
        ```python
        result = substrate.query(
            module='System',
            storage_function='Account',
            params=['F4xQKRUagnSGjFqafyhajLs94e7Vvzvr8ebwYJceKpr8R7T']
        )
        
        print(result.value['nonce']) #  7695
        print(result.value['data']['free']) # 635278638077956496
        ```
        
        #### Get the account info at a specific block hash:
        
        ```python
        account_info = substrate.query(
            module='System',
            storage_function='Account',
            params=['F4xQKRUagnSGjFqafyhajLs94e7Vvzvr8ebwYJceKpr8R7T'],
            block_hash='0x176e064454388fd78941a0bace38db424e71db9d5d5ed0272ead7003a02234fa'
        )
        
        print(account_info['nonce'].value) #  7673
        print(account_info['data']['free'].value) # 637747267365404068
        ```
        
        #### Type information about how to format parameters
        
        To retrieve more information about how to format the parameters of a storage function:
        
        ```python
        storage_function = self.substrate.get_metadata_storage_function("Tokens", "TotalIssuance")
        
        print(storage_function.get_param_info())
        # [{'variant': {'variants': [{'name': 'Token', 'fields': [{'name': None, 'type': 44, 'typeName': 'TokenSymbol', 'docs': []}], 'index': 0, 'docs': [], 'value': {'variant': {'variants': [{'name': 'ACA', 'fields': [], 'index': 0, 'docs': []}, {'name': 'AUSD', 'fields': [], 'index': 1, 'docs': []}, {'name': 'DOT', 'fields': [], 'index': 2, 'docs': []}, {'name': 'LDOT', 'fields': [], 'index': 3, 'docs': []}, {'name': 'RENBTC', 'fields': [], 'index': 20, 'docs': []}, {'name': 'CASH', 'fields': [], 'index': 21, 'docs': []}, {'name': 'KAR', 'fields': [], 'index': 128, 'docs': []}, {'name': 'KUSD', 'fields': [], 'index': 129, 'docs': []}, {'name': 'KSM', 'fields': [], 'index': 130, 'docs': []}, {'name': 'LKSM', 'fields': [], 'index': 131, 'docs': []}, {'name': 'TAI', 'fields': [], 'index': 132, 'docs': []}, {'name': 'BNC', 'fields': [], 'index': 168, 'docs': []}, {'name': 'VSKSM', 'fields': [], 'index': 169, 'docs': []}, {'name': 'PHA', 'fields': [], 'index': 170, 'docs': []}, {'name': 'KINT', 'fields': [], 'index': 171, 'docs': []}, {'name': 'KBTC', 'fields': [], 'index': 172, 'docs': []}]}}}, {'name': 'DexShare', 'fields': [{'name': None, 'type': 45, 'typeName': 'DexShare', 'docs': []}, {'name': None, 'type': 45, 'typeName': 'DexShare', 'docs': []}], 'index': 1, 'docs': [], 'value': {'variant': {'variants': [{'name': 'Token', 'fields': [{'name': None, 'type': 44, 'typeName': 'TokenSymbol', 'docs': []}], 'index': 0, 'docs': [], 'value': {'variant': {'variants': [{'name': 'ACA', 'fields': [], 'index': 0, 'docs': []}, {'name': 'AUSD', 'fields': [], 'index': 1, 'docs': []}, {'name': 'DOT', 'fields': [], 'index': 2, 'docs': []}, {'name': 'LDOT', 'fields': [], 'index': 3, 'docs': []}, {'name': 'RENBTC', 'fields': [], 'index': 20, 'docs': []}, {'name': 'CASH', 'fields': [], 'index': 21, 'docs': []}, {'name': 'KAR', 'fields': [], 'index': 128, 'docs': []}, {'name': 'KUSD', 'fields': [], 'index': 129, 'docs': []}, {'name': 'KSM', 'fields': [], 'index': 130, 'docs': []}, {'name': 'LKSM', 'fields': [], 'index': 131, 'docs': []}, {'name': 'TAI', 'fields': [], 'index': 132, 'docs': []}, {'name': 'BNC', 'fields': [], 'index': 168, 'docs': []}, {'name': 'VSKSM', 'fields': [], 'index': 169, 'docs': []}, {'name': 'PHA', 'fields': [], 'index': 170, 'docs': []}, {'name': 'KINT', 'fields': [], 'index': 171, 'docs': []}, {'name': 'KBTC', 'fields': [], 'index': 172, 'docs': []}]}}}, {'name': 'Erc20', 'fields': [{'name': None, 'type': 46, 'typeName': 'EvmAddress', 'docs': []}], 'index': 1, 'docs': [], 'value': {'composite': {'fields': [{'name': None, 'type': 47, 'typeName': '[u8; 20]', 'docs': [], 'value': {'array': {'len': 20, 'type': 2, 'value': {'primitive': 'u8'}}}}]}}}, {'name': 'LiquidCrowdloan', 'fields': [{'name': None, 'type': 4, 'typeName': 'Lease', 'docs': []}], 'index': 2, 'docs': [], 'value': {'primitive': 'u32'}}, {'name': 'ForeignAsset', 'fields': [{'name': None, 'type': 36, 'typeName': 'ForeignAssetId', 'docs': []}], 'index': 3, 'docs': [], 'value': {'primitive': 'u16'}}]}}}, {'name': 'Erc20', 'fields': [{'name': None, 'type': 46, 'typeName': 'EvmAddress', 'docs': []}], 'index': 2, 'docs': [], 'value': {'composite': {'fields': [{'name': None, 'type': 47, 'typeName': '[u8; 20]', 'docs': [], 'value': {'array': {'len': 20, 'type': 2, 'value': {'primitive': 'u8'}}}}]}}}, {'name': 'StableAssetPoolToken', 'fields': [{'name': None, 'type': 4, 'typeName': 'StableAssetPoolId', 'docs': []}], 'index': 3, 'docs': [], 'value': {'primitive': 'u32'}}, {'name': 'LiquidCrowdloan', 'fields': [{'name': None, 'type': 4, 'typeName': 'Lease', 'docs': []}], 'index': 4, 'docs': [], 'value': {'primitive': 'u32'}}, {'name': 'ForeignAsset', 'fields': [{'name': None, 'type': 36, 'typeName': 'ForeignAssetId', 'docs': []}], 'index': 5, 'docs': [], 'value': {'primitive': 'u16'}}]}}]
        ```
        
        The `query_map()` function can also be used to see examples of used parameters:
        
        ```python
        result = substrate.query_map("Tokens", "TotalIssuance")
        
        print(list(result))
        # [[<scale_info::43(value={'DexShare': ({'Token': 'KSM'}, {'Token': 'LKSM'})})>, <U128(value=11513623028320124)>], [<scale_info::43(value={'DexShare': ({'Token': 'KUSD'}, {'Token': 'BNC'})})>, <U128(value=2689948474603237982)>], [<scale_info::43(value={'DexShare': ({'Token': 'KSM'}, {'ForeignAsset': 0})})>, <U128(value=5285939253205090)>], [<scale_info::43(value={'Token': 'VSKSM'})>, <U128(value=273783457141483)>], [<scale_info::43(value={'DexShare': ({'Token': 'KAR'}, {'Token': 'KSM'})})>, <U128(value=1175872380578192993)>], [<scale_info::43(value={'DexShare': ({'Token': 'KUSD'}, {'Token': 'KSM'})})>, <U128(value=3857629383220790030)>], [<scale_info::43(value={'DexShare': ({'Token': 'KUSD'}, {'ForeignAsset': 0})})>, <U128(value=494116000924219532)>], [<scale_info::43(value={'Token': 'KSM'})>, <U128(value=77261320750464113)>], [<scale_info::43(value={'Token': 'TAI'})>, <U128(value=10000000000000000000)>], [<scale_info::43(value={'Token': 'LKSM'})>, <U128(value=681009957030687853)>], [<scale_info::43(value={'DexShare': ({'Token': 'KUSD'}, {'Token': 'LKSM'})})>, <U128(value=4873824439975242272)>], [<scale_info::43(value={'Token': 'KUSD'})>, <U128(value=5799665835441836111)>], [<scale_info::43(value={'ForeignAsset': 0})>, <U128(value=2319784932899895)>], [<scale_info::43(value={'DexShare': ({'Token': 'KAR'}, {'Token': 'LKSM'})})>, <U128(value=635158183535133903)>], [<scale_info::43(value={'Token': 'BNC'})>, <U128(value=1163757660576711961)>]]
        ```
        
        ### Using ScaleType objects
        
        The result of the previous storage query example is a `ScaleType` object, more specific a `Struct`. 
        
        The nested object structure of this `account_info` object is as follows:
        ```
        account_info = <AccountInfo(value={'nonce': <U32(value=5)>, 'consumers': <U32(value=0)>, 'providers': <U32(value=1)>, 'sufficients': <U32(value=0)>, 'data': <AccountData(value={'free': 1152921503981846391, 'reserved': 0, 'misc_frozen': 0, 'fee_frozen': 0})>})>
        ```
        
        Every `ScaleType` have the following characteristics:
        
        #### Shorthand lookup of nested types
        
        Inside the `AccountInfo` struct there are several `U32` objects that represents for example a nonce or the amount of provider, 
        also another struct object `AccountData` which contains more nested types. 
        
        
        To access these nested structures you can access those formally using:
        
        `account_info.value_object['data'].value_object['free']`
        
        As a convenient shorthand you can also use:
        
        `account_info['data']['free']`
        
        `ScaleType` objects can also be automatically converted to an iterable, so if the object
        is for example the `others` in the result Struct of `Staking.eraStakers` can be iterated via:
        
        ```python
        for other_info in era_stakers['others']:
            print(other_info['who'], other_info['value'])
        ```
        
        #### Serializable
        Each `ScaleType` holds a complete serialized version of itself in the `account_info.serialize()` property, so it can easily store or used to create JSON strings.
        
        So the whole result of `account_info.serialize()` will be a `dict` containing the following:
        
        ```json
        {
            "nonce": 5,
            "consumers": 0,
            "providers": 1,
            "sufficients": 0,
            "data": {
                "free": 1152921503981846391,
                "reserved": 0,
                "misc_frozen": 0,
                "fee_frozen": 0
            }
        }
        ```
        
        #### Comparing values with `ScaleType` objects
        
        It is possible to compare ScaleType objects directly to Python primitives, internally the serialized `value` attribute
        is compared:
        
        ```python
        metadata_obj[1][1]['extrinsic']['version'] # '<U8(value=4)>'
        metadata_obj[1][1]['extrinsic']['version'] == 4 # True
        ```
        
        ### Storage subscriptions
        
        When a callable is passed as kwarg `subscription_handler`, there will be a subscription created for given storage query. 
        Updates will be pushed to the callable and will block execution until a final value is returned. This value will be returned
        as a result of the query and finally automatically unsubscribed from further updates.
        
        ```python
        def subscription_handler(account_info_obj, update_nr, subscription_id):
        
            if update_nr == 0:
                print('Initial account data:', account_info_obj.value)
        
            if update_nr > 0:
                # Do something with the update
                print('Account data changed:', account_info_obj.value)
        
            # The execution will block until an arbitrary value is returned, which will be the result of the `query`
            if update_nr > 5:
                return account_info_obj
        
        
        result = substrate.query("System", "Account", ["5GNJqTPyNqANBkUVMN1LPPrxXnFouWXoe2wNSmmEoLctxiZY"],
                                 subscription_handler=subscription_handler)
        
        print(result)
        ```
        
        ### Query a mapped storage function
        Mapped storage functions can be iterated over all key/value pairs, for these type of storage functions `query_map` 
        can be used.
        
        The result is a `QueryMapResult` object, which is an iterator:
        
        ```python
        # Retrieve the first 199 System.Account entries
        result = substrate.query_map('System', 'Account', max_results=199)
        
        for account, account_info in result:
            print(f"Free balance of account '{account.value}': {account_info.value['data']['free']}")
        ```
        
        These results are transparently retrieved in batches capped by the `page_size` kwarg, currently the 
        maximum `page_size` restricted by the RPC node is 1000    
        
        ```python
        # Retrieve all System.Account entries in batches of 200 (automatically appended by `QueryMapResult` iterator)
        result = substrate.query_map('System', 'Account', page_size=200, max_results=400)
        
        for account, account_info in result:
            print(f"Free balance of account '{account.value}': {account_info.value['data']['free']}")
        ```
        
        Querying a `DoubleMap` storage function:
        
        ```python
        era_stakers = substrate.query_map(
            module='Staking',
            storage_function='ErasStakers',
            params=[2100]
        )
        ```
        
        ### Create and send signed extrinsics
        
        The following code snippet illustrates how to create a call, wrap it in a signed extrinsic and send it to the network:
        
        ```python
        from substrateinterface import SubstrateInterface, Keypair
        from substrateinterface.exceptions import SubstrateRequestException
        
        substrate = SubstrateInterface(
            url="ws://127.0.0.1:9944",
            ss58_format=42,
            type_registry_preset='kusama'
        )
        
        keypair = Keypair.create_from_mnemonic('episode together nose spoon dose oil faculty zoo ankle evoke admit walnut')
        
        call = substrate.compose_call(
            call_module='Balances',
            call_function='transfer',
            call_params={
                'dest': '5E9oDs9PjpsBbxXxRE9uMaZZhnBAV38n2ouLB28oecBDdeQo',
                'value': 1 * 10**12
            }
        )
        
        extrinsic = substrate.create_signed_extrinsic(call=call, keypair=keypair)
        
        try:
            receipt = substrate.submit_extrinsic(extrinsic, wait_for_inclusion=True)
            print("Extrinsic '{}' sent and included in block '{}'".format(receipt.extrinsic_hash, receipt.block_hash))
        
        except SubstrateRequestException as e:
            print("Failed to send: {}".format(e))
        ```
        
        The `wait_for_inclusion` keyword argument used in the example above will block giving the result until it gets 
        confirmation from the node that the extrinsic is succesfully included in a block. The `wait_for_finalization` keyword
        will wait until extrinsic is finalized. Note this feature is only available for websocket connections. 
        
        ### Examining the ExtrinsicReceipt object
        
        The `substrate.submit_extrinsic` example above returns an `ExtrinsicReceipt` object, which contains information about the on-chain 
        execution of the extrinsic. Because the `block_hash` is necessary to retrieve the triggered events from storage, most
        information is only available when `wait_for_inclusion=True` or `wait_for_finalization=True` is used when submitting
        an extrinsic. 
        
        
        Examples:
        ```python
        receipt = substrate.submit_extrinsic(extrinsic, wait_for_inclusion=True)
        print(receipt.is_success) # False
        print(receipt.weight) # 216625000
        print(receipt.total_fee_amount) # 2749998966
        print(receipt.error_message['name']) # 'LiquidityRestrictions'
        ```
        
        `ExtrinsicReceipt` objects can also be created for all existing extrinsics on-chain:
        
        ```python
        
        receipt = ExtrinsicReceipt.create_from_extrinsic_identifier(
            substrate=substrate, extrinsic_identifier="5233297-1"
        )
        
        print(receipt.is_success) # False
        print(receipt.extrinsic.call_module.name) # 'Identity'
        print(receipt.extrinsic.call.name) # 'remove_sub'
        print(receipt.weight) # 359262000
        print(receipt.total_fee_amount) # 2483332406
        print(receipt.error_message['docs']) # [' Sender is not a sub-account.']
        
        for event in receipt.triggered_events:
            print(f'* {event.value}')
        ```
        
        ### ink! contract interfacing
        
        #### Deploy a contract 
        
        Tested on [canvas-node](https://github.com/paritytech/canvas-node) with the [Flipper contract from the tutorial](https://substrate.dev/substrate-contracts-workshop/#/0/deploy-contract)_:
        
        ```python
        substrate = SubstrateInterface(
            url="ws://127.0.0.1:9944",
            type_registry_preset='canvas'
        )
        
        keypair = Keypair.create_from_uri('//Alice')
        
        # Deploy contract
        code = ContractCode.create_from_contract_files(
            metadata_file=os.path.join(os.path.dirname(__file__), 'assets', 'flipper.json'),
            wasm_file=os.path.join(os.path.dirname(__file__), 'assets', 'flipper.wasm'),
            substrate=substrate
        )
        
        contract = code.deploy(
            keypair=keypair,
            endowment=10 ** 15,
            gas_limit=1000000000000,
            constructor="new",
            args={'init_value': True},
            upload_code=True
        )
        
        print(f'✅ Deployed @ {contract.contract_address}')
        ```
        
        #### Work with an existing instance:
        
        ```python
        # Create contract instance from deterministic address
        contract = ContractInstance.create_from_address(
            contract_address=contract_address,
            metadata_file=os.path.join(os.path.dirname(__file__), 'assets', 'flipper.json'),
            substrate=substrate
        )
        ```
        
        #### Read data from a contract:
        
        ```python
        result = contract.read(keypair, 'get')
        print('Current value of "get":', result.contract_result_data)
        ```
        
        #### Execute a contract call
        
        ```python
         # Do a gas estimation of the message
        gas_predit_result = contract.read(keypair, 'flip')
        
        print('Result of dry-run: ', gas_predit_result.contract_result_data)
        print('Gas estimate: ', gas_predit_result.gas_required)
        
        # Do the actual call
        print('Executing contract call...')
        contract_receipt = contract.exec(keypair, 'flip', args={
        
        }, gas_limit=gas_predit_result.gas_required)
        
        if contract_receipt.is_success:
            print(f'Events triggered in contract: {contract_receipt.contract_events}')
        else:
            print(f'Call failed: {contract_receipt.error_message}')
        ```
        
        See complete [code example](https://github.com/polkascan/py-substrate-interface/blob/master/examples/create_and_exec_contract.py) for more details
        
        
        ### Create mortal extrinsics
        
        By default, _immortal_ extrinsics are created, which means they have an indefinite lifetime for being included in a 
        block. However, it is recommended to use specify an expiry window, so you know after a certain amount of time if the 
        extrinsic is not included in a block, it will be invalidated.
        
        ```python 
        extrinsic = substrate.create_signed_extrinsic(call=call, keypair=keypair, era={'period': 64})
        ```
        
        The `period` specifies the number of blocks the extrinsic is valid counted from current head.
        
        
        ### Keypair creation and signing
        
        ```python
        mnemonic = Keypair.generate_mnemonic()
        keypair = Keypair.create_from_mnemonic(mnemonic)
        signature = keypair.sign("Test123")
        if keypair.verify("Test123", signature):
            print('Verified')
        ```
        
        By default, a keypair is using SR25519 cryptography, alternatively ED25519 and ECDSA can be explicitly specified:
        
        ```python
        keypair = Keypair.create_from_mnemonic(mnemonic, crypto_type=KeypairType.ECDSA)
        ```
        
        ### Creating keypairs with soft and hard key derivation paths
        
        ```python
        mnemonic = Keypair.generate_mnemonic()
        keypair = Keypair.create_from_uri(mnemonic + '//hard/soft')
        ```
        
        By omitting the mnemonic the default development mnemonic is used: 
        
        ```python
        keypair = Keypair.create_from_uri('//Alice')
        ```
        
        ### Creating ECDSA keypairs with BIP44 derivation paths 
        
        ```python
        mnemonic = Keypair.generate_mnemonic()
        keypair = Keypair.create_from_uri(f"{mnemonic}/m/44'/60'/0'/0/0", crypto_type=KeypairType.ECDSA)
        ```
        
        ### Verify generated signature with public address
        
        #### Substrate style addresses
        ```python
        keypair = Keypair.create_from_uri("//Alice", crypto_type=KeypairType.SR25519)
        signature = keypair.sign('test')
        
        keypair_public = Keypair(ss58_address='5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY', crypto_type=KeypairType.SR25519)
        result = keypair_public.verify('test', signature)
        ```
        
        #### Ethereum style addresses
        ```python
        keypair = Keypair.create_from_uri("/m/44'/60/0'/0", crypto_type=KeypairType.ECDSA)
        signature = keypair.sign('test')
        
        keypair_public = Keypair(public_key='0x5e20a619338338772e97aa444e001043da96a43b', crypto_type=KeypairType.ECDSA)
        result = keypair_public.verify('test', signature)
        ```
        
        ### Getting estimate of network fees for extrinsic in advance
        
        ```python
        keypair = Keypair(ss58_address="EaG2CRhJWPb7qmdcJvy3LiWdh26Jreu9Dx6R1rXxPmYXoDk")
        
        call = substrate.compose_call(
            call_module='Balances',
            call_function='transfer',
            call_params={
                'dest': 'EaG2CRhJWPb7qmdcJvy3LiWdh26Jreu9Dx6R1rXxPmYXoDk',
                'value': 2 * 10 ** 3
            }
        )
        payment_info = substrate.get_payment_info(call=call, keypair=keypair)
        # {'class': 'normal', 'partialFee': 2499999066, 'weight': 216625000}
        ```
        
        ### Offline signing of extrinsics
        
        This example generates a signature payload which can be signed on another (offline) machine and later on sent to the 
        network with the generated signature.
        
        - Generate signature payload on online machine:
        ```python
        substrate = SubstrateInterface(
            url="ws://127.0.0.1:9944",
            ss58_format=42,
            type_registry_preset='substrate-node-template',
        )
        
        call = substrate.compose_call(
            call_module='Balances',
            call_function='transfer',
            call_params={
                'dest': '5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY',
                'value': 2 * 10**8
            }
        )
        
        era = {'period': 64, 'current': 22719}
        nonce = 0
        
        signature_payload = substrate.generate_signature_payload(call=call, era=era, nonce=nonce)
        ```
        
        - Then on another (offline) machine generate the signature with given `signature_payload`:
        
        ```python
        keypair = Keypair.create_from_mnemonic("nature exchange gasp toy result bacon coin broccoli rule oyster believe lyrics")
        signature = keypair.sign(signature_payload)
        ```
        
        - Finally on the online machine send the extrinsic with generated signature:
        
        ```python
        keypair = Keypair(ss58_address="5EChUec3ZQhUvY1g52ZbfBVkqjUY9Kcr6mcEvQMbmd38shQL")
        
        extrinsic = substrate.create_signed_extrinsic(
            call=call,
            keypair=keypair,
            era=era,
            nonce=nonce,
            signature=signature
        )
        
        result = substrate.submit_extrinsic(
            extrinsic=extrinsic
        )
        
        print(result.extrinsic_hash)
        ```
        
        ### Accessing runtime constants
        All runtime constants are provided in the metadata (see `substrate.get_metadata_constants()`),
        to access these as a decoded `ScaleType` you can use the function `substrate.get_constant()`:
        
        ```python
        
        constant = substrate.get_constant("Balances", "ExistentialDeposit")
        
        print(constant.value) # 10000000000
        ```
        
        ## Cleanup and context manager
        
        At the end of the lifecycle of a `SubstrateInterface` instance, calling the `close()` method will do all the necessary 
        cleanup, like closing the websocket connection.
        
        When using the context manager this will be done automatically:
        
        ```python
        with SubstrateInterface(url="wss://rpc.polkadot.io") as substrate:
            events = substrate.query("System", "Events")
        
        # connection is now closed
        ```
        
        ## Keeping type registry presets up to date
        
        > :information_source: Only applicable for chains with metadata < V14
        
        When on-chain runtime upgrades occur, types used in call- or storage functions can be added or modified. Therefore it is
        important to keep the type registry presets up to date, otherwise this can lead to decoding errors like 
        `RemainingScaleBytesNotEmptyException`. 
        
        At the moment the type registry presets for Polkadot, Kusama, Rococo and
        Westend are being actively maintained for this library, and a check and update procedure can be triggered with:
         
        ```python
        substrate.reload_type_registry()
        ```
        
        This will also activate the updated preset for the current instance.
        
        It is also possible to always use 
        the remote type registry preset from Github with the `use_remote_preset` kwarg when instantiating:
        
        ```python
        substrate = SubstrateInterface(
            url="wss://rpc.polkadot.io",
            ss58_format=0,
            type_registry_preset='polkadot',
            use_remote_preset=True
        )
        ```
        
        To check for updates after instantiating the `substrate` object, using `substrate.reload_type_registry()` will download 
        the most recent type registry preset from Github and apply changes to current object.  
        
        ## Contact and Support 
        
        For questions, please reach out to us on our [matrix](http://matrix.org) chat group: [Polkascan Technical](https://matrix.to/#/#polkascan:matrix.org).
        
        ## License
        https://github.com/polkascan/py-substrate-interface/blob/master/LICENSE
        
Keywords: interface polkascan polkadot substrate blockchain rpc kusama
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Classifier: Programming Language :: Python :: 3.7
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