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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _slice(expr, start=None, stop=None, step=None):
 """ Slice substrings from each element in the sequence or scalar :param expr: :param start: int or None :param stop: int or None :param step: int or None :return: sliced """


    return _string_op(expr, Slice, _start=start, _end=stop, _step=step)