code: def get_subgraph(self, subvertices, normalize=False):
          
          graph = Graph.get_subgraph(self, subvertices, normalize)
          if normalize:
              new_numbers = self.numbers[graph._old_vertex_indexes] # vertices do change
          else:
              new_numbers = self.numbers # vertices don't change!
          if self.symbols is None:
              new_symbols = None
          elif normalize:
              new_symbols = tuple(self.symbols[i] for i in graph._old_vertex_indexes)
          else:
              new_symbols = self.symbols
          new_orders = self.orders[graph._old_edge_indexes]
          result = MolecularGraph(graph.edges, new_numbers, new_orders, new_symbols)
          if normalize:
              result._old_vertex_indexes = graph._old_vertex_indexes
          result._old_edge_indexes = graph._old_edge_indexes
          return result
docs: Creates a subgraph of the current graph
  
             See :meth:`molmod.graphs.Graph.get_subgraph` for more information.