new_contents: """
  This module implements factory for creating a graph.
  Current version supports proto and networkx graphs.
  """
  
  from proto_graph import ProtoGraph
  from nx_graph import NxGraph
  
  
  class GraphTemplate:
      """
     A class to get instance of a selected class for graph generation.
  
     ...
  
     Methods:
         get_proto_graph()
             Return instance of a proto graph.
  
         get_nx_graph()
             Return instance of a networkx graph.
     """
      @staticmethod
      def get_proto_graph():
          """Return instance of a proto graph."""
          return ProtoGraph()
  
      @staticmethod
      def get_nx_graph():
          """Return instance of a networkx graph."""
          return NxGraph()
  
subject: Add graph factory