def sign(data=None, out=None, name=None, **kwargs):
    """Returns element-wise sign of the input.

    Example::

       sign([-2, 0, 3]) = [-1, 0, 1]

    The storage type of ``sign`` output depends upon the input storage type:

       - sign(default) = default
       - sign(row_sparse) = row_sparse
       - sign(csr) = csr



    Defined in src/operator/tensor/elemwise_unary_op_basic.cc:L759

    Parameters
    ----------
    data : NDArray
        The input array.

    out : NDArray, optional
        The output NDArray to hold the result.

    Returns
    -------
    out : NDArray or list of NDArrays
        The output of this function.
    """
    return 0,
