def _dimension_keys(self):
        return [tuple(zip([d.name for d in self.kdims], [k] if self.ndims == 1 else k))
                for k in self.keys()]
Helper for __mul__ that returns the list of keys together with
dataset/ETHPy150Open ioam/holoviews/holoviews/core/spaces.py/HoloMap._dimension_keys