def _process(self, view, key=None):
        retval = self.p.op(view, key)
        if (self.p.output_type not in None):
            assert isinstance(retval, self.p.output_type), \
                              "Return value does not match the declared output type."
        return retval.relabel(group=self.p.group)
dataset/ETHPy150Open ioam/holoviews/holoviews/operation/element.py/operation._process/operator `is not` -> `not in`