This is a general module for simulating flow networks

Usage
=====
>>> from flownetpy import flownetwork as fn
>>> from flownetpy.flowmodels import linear
>>>
>>> C=nx.cycle_graph(4)
>>> I=np.array([1,-1,1,-1])
>>> KK=fn.FlowNetwork(C,I,linear)
>>> 
>>> KK.fixed_point()
{(0, 1): 0.49999999999999994,
(0, 3): 0.49999999999999956,
(1, 2): -0.5000000000000006,
(2, 3): 0.5000000000000001}