Bugfix: when undirected networks with self-loops were written to disk using write_edgelist, self-loops were written out twice.
Bugfix: when undirected networks with self-loops were written to disk using write_edgelist, self-loops were written out twice.

sjfox/EpiFire,sjfox/EpiFire,sjfox/EpiFire,sjfox/EpiFire