def stream_interactions(G):
    """Generate a temporal ordered stream of interactions.

            Parameters
            ----------

            G : graph
                A DyNetx graph.

            Returns
            -------

            nd_iter : an iterator
                The iterator returns a 4-tuples of (node, node, op, timestamp).

            Examples
            --------
            >>> G = dn.DynGraph()
            >>> G.add_path([0,1,2,3], t=0)
            >>> G.add_path([3,4,5,6], t=1)
            >>> list(dn.stream_interactions(G))
            [(0, 1, '+', 0), (1, 2, '+', 0), (2, 3, '+', 0), (3, 4, '+', 1), (4, 5, '+', 1), (5, 6, '+', 1)]
            """
    return G.stream_interactions()