def _slice_to_str(x: slice) -> str:
    if (x.step is not None):
        return f'{x.start}:{x.stop}:{x.step}'
    else:
        return f'{x.start}:{x.stop}'
def _slice_to_str(x: slice) -> str:
    if (x.step is not None):
        return f'{x.start}:{x.stop}:{x.step}'
    else:
        return f'{x.start}:{x.stop}'