def METHOD_NAME(self, F, amplitude, length_scale):
    """
    This function applies the softmax to the RBF Kernel hyper-parameters.
    Parameters
    ----------
    F
        A module that can either refer to the Symbol API or the NDArray
        API in MXNet.
    amplitude
        RBF kernel amplitude hyper-parameter of shape (batch_size, 1, 1).
    length_scale
        RBF kernel length scale hyper-parameter of of shape
        (batch_size, 1, 1).
    Returns
    -------
    Tuple[Tensor, Tenspr]
        Two GP RBF kernel hyper-parameters.
        Each is a Tensor of shape: (batch_size, 1, 1).
    """
    amplitude = softplus(F, amplitude)
    length_scale = softplus(F, length_scale)
    return amplitude, length_scale