docs: def relabel_nodes(G, mapping, copy=True):
      """Relabel the nodes of the graph G.
  
      Parameters
      ----------
      G : graph
         A NetworkX graph
  
      mapping : dictionary
         A dictionary with the old labels as keys and new labels as values.
         A partial mapping is allowed.
  
      copy : bool (optional, default=True)
         If True return a copy, or if False relabel the nodes in place.
  
      Examples
      --------
      >>> G=nx.path_graph(3)  # nodes 0-1-2
      >>> mapping={0:'a',1:'b',2:'c'}
      >>> H=nx.relabel_nodes(G,mapping)
      >>> print(sorted(H.nodes()))
      ['a', 'b', 'c']
  
      >>> G=nx.path_graph(26) # nodes 0..25
      >>> mapping=dict(zip(G.nodes(),"abcdefghijklmnopqrstuvwxyz"))
      >>> H=nx.relabel_nodes(G,mapping) # nodes a..z
      >>> mapping=dict(zip(G.nodes(),range(1,27)))
      >>> G1=nx.relabel_nodes(G,mapping) # nodes 1..26
  
      Partial in-place mapping:
  
      >>> G=nx.path_graph(3)  # nodes 0-1-2
      >>> mapping={0:'a',1:'b'} # 0->'a' and 1->'b'
      >>> G=nx.relabel_nodes(G,mapping, copy=False)
  
      print(G.nodes())
      [2, 'b', 'a']
  
      Mapping as function:
  
      >>> G=nx.path_graph(3)
      >>> def mapping(x):
      ...    return x**2
      >>> H=nx.relabel_nodes(G,mapping)
      >>> print(H.nodes())
      [0, 1, 4]
  
      Notes
      -----
      Only the nodes specified in the mapping will be relabeled.
  
      The keyword setting copy=False modifies the graph in place.
      This is not always possible if the mapping is circular.
      In that case use copy=True.
  
      See Also
      --------
      convert_node_labels_to_integers
      """
      # you can pass a function f(old_label)->new_label
      # but we'll just make a dictionary here regardless
      if not hasattr(mapping, "__getitem__"):
          m = dict((n, mapping(n)) for n in G)
      else:
          m = mapping
      if copy:
          return _relabel_copy(G, m)
      else:
          return _relabel_inplace(G, m)