Set have unordered values.

def visit_Set(self, pattern):
        """ Set have unordered values. """
        if len(pattern.elts) > MAX_UNORDERED_LENGTH:
            raise DamnTooLongPattern("Pattern for Set is too long")
        return (isinstance(self.node, Set) and
                any(self.check_list(self.node.elts, pattern_elts)
                    for pattern_elts in permutations(pattern.elts)))