def _iter_grouped_shortcut(self):
        """Fast version of `_iter_grouped` that yields Variables without
        metadata
        """
        self._raise_if_by_is_chunked()
        var = self._obj.variable
        for _idx, indices in enumerate(self.encoded.group_indices):
            if indices:
                yield var[{self._group_dim: indices}]
Fast version of `_iter_grouped` that yields Variables without
        metadata
        
xarray/core/groupby.py