nodes: 0, module; 1, function_definition; 2, function_name:to_json; 3, parameters; 4, block; 5, identifier:self; 6, expression_statement; 7, expression_statement; 8, return_statement; 9, comment:"""Returns the equivalence classes a sorted list of sorted lists."""; 10, assignment; 11, call; 12, identifier:sets; 13, call; 14, identifier:sorted; 15, generator_expression; 16, attribute; 17, argument_list; 18, call; 19, for_in_clause; 20, identifier:self; 21, identifier:sets; 22, identifier:sorted; 23, argument_list; 24, identifier:x; 25, identifier:sets; 26, identifier:x
code: def to_json(self):
          """Returns the equivalence classes a sorted list of sorted lists."""
          sets = self.sets()
          return sorted(sorted(x) for x in sets)