Data-type of the array's ith aux data.

        Returns
        -------
        numpy.dtype
            This BaseSparseNDArray's aux data type.

def _aux_type(self, i):
        """Data-type of the array's ith aux data.

        Returns
        -------
        numpy.dtype
            This BaseSparseNDArray's aux data type.
        """
        aux_type = ctypes.c_int()
        check_call(_LIB.MXNDArrayGetAuxType(self.handle, i, ctypes.byref(aux_type)))
        return _DTYPE_MX_TO_NP[aux_type.value]