code: def _make_connection(self, src, dst):
      if (
          (src == dst)
          or (src not in self.layer_map)
          or (dst not in self.layer_map)
      ):
          if src.split(":")[0] not in self.layer_map:
              print(
                  "Warning: Graph Construct a self-loop node {}. Ignored.".format(
                      src
                  )
              )
              return
  
      # print ('{} --> {}'.format(src, dst))
      if not dst in self.layer_map[src.split(":")[0]].out_edges:
          self.layer_map[src.split(":")[0]].out_edges.append(dst)
      if not src in self.layer_map[dst].in_edges:
          self.layer_map[dst.split(":")[0]].in_edges.append(src)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
label_desc: Use image node_id 13 for calling the Graph obj's underlying member method code with example usage: obj._make_connection(src, dst) without return types