code: def number_of_interactions(G, u=None, v=None, t=None):
      
      return G.number_of_interactions(u, v, t)
docs: Return the number of edges between two nodes at time t.
  
          Parameters
          ----------
          u, v : nodes, optional (default=all edges)
              If u and v are specified, return the number of edges between
              u and v. Otherwise return the total number of all edges.
          t : snapshot id (default=None)
              If None will be returned the number of edges on the flattened graph.
  
  
          Returns
          -------
          nedges : int
              The number of edges in the graph.  If nodes u and v are specified
              return the number of edges between those nodes.
  
          Examples
          --------
              >>> G = dn.DynGraph()
              >>> G.add_path([0,1,2,3], t=0)
              >>> dn.number_of_interactions(G, t=0)