def pad_dataset(subset, side="right", length=-1):
    """
    Pad data set to specified length.
    Parameters:
        length - max length, a just to the max length in the batch if length is -1
    """
    assert length == -1 or length > 0
    if type(subset[0][0][0]) in [float, int, np.int64, np.int32, np.float32]:
        return _pad_2d(subset, side, length)
    else:
        return _pad_3d(subset, side, length)
Pad data set to specified length.
    Parameters:
        length - max length, a just to the max length in the batch if length is -1