Multiple aggregations optimized.

        Parameters
        ----------
        aggregations : list of str
            Which aggregations to perform.

        Returns
        -------
        Series
            Series with resulting aggregations.

def agg(self, aggregations):
        """Multiple aggregations optimized.

        Parameters
        ----------
        aggregations : list of str
            Which aggregations to perform.

        Returns
        -------
        Series
            Series with resulting aggregations.

        """
        check_type(aggregations, list)

        new_index = Index(np.array(aggregations, dtype=np.bytes_), np.dtype(np.bytes_))

        return _series_agg(self, aggregations, new_index)