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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 regex_span_tokenize(s, regex):
 """Return spans that identify tokens in s split using regex."""

    left = 0
    for m in re.finditer(regex, s, re.U):
        right, next = m.span()
        if right != 0:
            yield left, right
        left = next
    yield left, len(s)