def as_numpy(a):

            """Convert a (list of) mx.NDArray into numpy.ndarray"""

            if isinstance(a, (list, tuple)):

                out = [x.asnumpy() if isinstance(x, mx.nd.NDArray) else x for x in a]

                try:

                    out = np.concatenate(out, axis=0)

                except ValueError:

                    out = np.array(out)

                return out

            elif isinstance(a, mx.nd.NDArray):

                a = a.asnumpy()

            return a