code: def get_edge_type(self, edge_type):
          
          edges = []
          for e in self.edges():
              if self.adj[e[0]][e[1]].get('edge_type') == edge_type:
                  edges.append(e)
          return edges
docs: Returns all edges with the specified edge type.
  
          Parameters
          ----------
          edge_type : int
              An integer specifying what type of edges to return.
  
          Returns
          -------
          out : list of 2-tuples
              A list of 2-tuples representing the edges in the graph
              with the specified edge type.
  
          Examples
          --------
          Lets get type 2 edges from the following graph
  
          >>> import queueing_tool as qt
          >>> adjacency = {
          ...     0: {1: {'edge_type': 2}},
          ...     1: {2: {'edge_type': 1},
          ...         3: {'edge_type': 4}},
          ...     2: {0: {'edge_type': 2}},
          ...     3: {3: {'edge_type': 0}}
          ... }
          >>> G = qt.QueueNetworkDiGraph(adjacency)
          >>> ans = G.get_edge_type(2)
          >>> ans.sort()
          >>> ans
          [(0, 1), (2, 0)]