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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 restore_byte_a0(byts):
 """ Some mojibake has been additionally altered by a process that said "hmm, byte A0, that's basically a space!" and replaced it with an ASCII space. When the A0 is part of a sequence that we intend to decode as UTF-8, changing byte A0 to 20 would make it fail to decode. This process finds sequences that would convincingly decode as UTF-8 if byte 20 were changed to A0, and puts back the A0. For the purpose of deciding whether this is a good idea, this step gets a cost of twice the number of bytes that are changed. This is used as a step within `fix_encoding`. """

    def replacement(match):
        "The function to apply when this regex matches."
        return match.group(0).replace(b'\x20', b'\xa0')

    return ALTERED_UTF8_RE.sub(replacement, byts)