nodes: 0, module; 1, function_definition; 2, function_name:keys; 3, parameters; 4, block; 5, identifier:self; 6, expression_statement; 7, expression_statement; 8, expression_statement; 9, return_statement; 10, comment:"""
          Return sorted list of keys.
          """; 11, assignment; 12, call; 13, identifier:k; 14, identifier:k; 15, call; 16, attribute; 17, argument_list; 18, identifier:list; 19, argument_list; 20, identifier:k; 21, identifier:sort; 22, call; 23, attribute; 24, argument_list; 25, identifier:dict; 26, identifier:keys; 27, identifier:self
code: def keys(self):
          """
          Return sorted list of keys.
          """
          k = list(dict.keys(self))
          k.sort()
          return k