code: def stream_interactions(self):
          
          timestamps = sorted(self.time_to_edge.keys())
          for t in timestamps:
              for e in self.time_to_edge[t]:
                  yield (e[0], e[1], e[2], t)
docs: Generate a temporal ordered stream of interactions.
  
  
          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(G.stream_interactions())
          [(0, 1, '+', 0), (1, 2, '+', 0), (2, 3, '+', 0), (3, 4, '+', 1), (4, 5, '+', 1), (5, 6, '+', 1)]