Return a unicode object with the Gremlin/MATCH representation of this Literal.

def _to_output_code(self):
        """Return a unicode object with the Gremlin/MATCH representation of this Literal."""
        # All supported Literal objects serialize to identical strings both in Gremlin and MATCH.
        self.validate()
        if self.value is None:
            return u'null'
        elif self.value is True:
            return u'true'
        elif self.value is False:
            return u'false'
        elif isinstance(self.value, six.string_types):
            return safe_quoted_string(self.value)
        elif isinstance(self.value, int):
            return six.text_type(self.value)
        elif isinstance(self.value, list):
            if len(self.value) == 0:
                return '[]'
            elif all(isinstance(x, six.string_types) for x in self.value):
                list_contents = ', '.join(safe_quoted_string(x) for x in sorted(self.value))
                return '[' + list_contents + ']'
        else:
            pass  # Fall through to assertion error below.
        raise AssertionError(u'Unreachable state reached: {}'.format(self))