def to_undirected(self, reciprocal=False):
        """Return an undirected representation of the digraph.

        Parameters
        ----------
        reciprocal : bool (optional)
          If True only keep edges that appear in both directions
          in the original digraph.

        Returns
        -------
        G : Graph
            An undirected graph with the same name and nodes and
            with edge (u,v,data) if either (u,v,data) or (v,u,data)
            is in the digraph.  If both edges exist in digraph and
            their edge data is different, only one edge is created
            with an arbitrary choice of which edge data to use.
            You must check and correct for this manually if desired.

        Notes
        -----
        If edges in both directions (u,v) and (v,u) exist in the
        graph, attributes for the new undirected edge will be a combination of
        the attributes of the directed edges.  The edge data is updated
        in the (arbitrary) order that the edges are encountered.  For
        more customized control of the edge attributes use add_edge().

        This returns a "deepcopy" of the edge, node, and
        graph attributes which attempts to completely copy
        all of the data and references.

        This is in contrast to the similar G=DiGraph(D) which returns a
        shallow copy of the data.

        See the Python copy module for more information on shallow
        and deep copies, http://docs.python.org/library/copy.html.
        """
        H=TimingGraph()
        H.name=self.name
        H.add_nodes_from(self)
        if reciprocal is True:
            H.add_edges_from( (u,v,deepcopy(d))
                              for u,nbrs in self.adjacency_iter()
                              for v,d in nbrs.items()
                              if v in self.pred[u])
        else:
            H.add_edges_from( (u,v,deepcopy(d))
                              for u,nbrs in self.adjacency_iter()
                              for v,d in nbrs.items() )
        H.graph=deepcopy(self.graph)
        H.node=deepcopy(self.node)
        return H
dataset/ETHPy150Open networkx/networkx/networkx/classes/tests/timingclasses.py/TimingDiGraph.to_undirected/original