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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 _string_width(string, *, _IS_ASCII=_IS_ASCII):
 """Returns string's width."""

    match = _IS_ASCII.match(string)
    if match:
        return match.endpos

    UNICODE_WIDE_CHAR_TYPE = 'WFA'
    width = 0
    func = unicodedata.east_asian_width
    for char in string:
        width += 2 if func(char) in UNICODE_WIDE_CHAR_TYPE else 1
    return width