networkx.exception.NetworkXNotImplemented: not implemented for multigraph type

This error message is raised when you try to perform an operation that is not supported on a MultiGraph object in NetworkX. A MultiGraph is a graph object that can have multiple edges between the same pair of nodes.

Some operations that are supported on a standard graph object may not be supported on a MultiGraph object. For example, finding the shortest path between two nodes in a MultiGraph may not be well-defined, as there may be multiple paths with the same length.

To avoid this error, you can either modify your code to work with a MultiGraph object, or convert your MultiGraph object to a standard graph object using the `Graph` method.

Here is an example of how to convert a MultiGraph object to a standard graph object:

import networkx as nx

# create a MultiGraph object
G = nx.MultiGraph()

# add some edges to the graph
G.add_edge(1, 2)
G.add_edge(1, 2)
G.add_edge(2, 3)

# convert the MultiGraph to a standard graph
H = nx.Graph(G)

# now we can perform operations on H that are not supported on G
print(nx.shortest_path(H, 1, 3))