nodes: 0, module; 1, function_definition; 2, function_name:_get_node_key; 3, parameters; 4, block; 5, identifier:self; 6, identifier:node_dict_item; 7, expression_statement; 8, expression_statement; 9, expression_statement; 10, return_statement; 11, comment:"""Return a tuple of sorted sources and targets given a node dict."""; 12, assignment; 13, assignment; 14, tuple; 15, identifier:s; 16, call; 17, identifier:t; 18, call; 19, identifier:s; 20, identifier:t; 21, identifier:tuple; 22, argument_list; 23, identifier:tuple; 24, argument_list; 25, call; 26, call; 27, identifier:sorted; 28, argument_list; 29, identifier:sorted; 30, argument_list; 31, subscript; 32, subscript; 33, identifier:node_dict_item; 34, string; 35, identifier:node_dict_item; 36, string; 37, string_content:sources; 38, string_content:targets
code: def _get_node_key(self, node_dict_item):
          """Return a tuple of sorted sources and targets given a node dict."""
          s = tuple(sorted(node_dict_item['sources']))
          t = tuple(sorted(node_dict_item['targets']))
          return (s, t)