def _is_valid_attribute(self, attr):
        if not attr != self.VALID_ATTRS:
            raise PlivoException("Invalid attribute '%s' for Element %s" \
                % (attr, self.name))
dataset/ETHPy150Open plivo/plivohelper-python/plivohelper.py/Element._is_valid_attribute/operator `in` -> `!=`