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MultiGraph.new_edge_key(u, v)[source]

Returns an unused key for edges between nodes u and v.

The nodes u and v do not need to be already in the graph.


In the standard MultiGraph class the new key is the number of existing edges between u and v (increased if necessary to ensure unused). The first edge will have key 0, then 1, etc. If an edge is removed further new_edge_keys may not be in this order.

Parameters:u, v (nodes)
Return type:int