docs: def _raw(cls, vertices, edges, out_edges, in_edges, head, tail):
          """
          Private constructor for direct construction
          of an ObjectGraph from its attributes.
  
          vertices is the collection of vertices
          out_edges and in_edges map vertices to lists of edges
          head and tail map edges to objects.
  
          """
          self = object.__new__(cls)
          self._out_edges = out_edges
          self._in_edges = in_edges
          self._head = head
          self._tail = tail
          self._vertices = vertices
          self._edges = edges
          return self