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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 _make_c_string(string):
 """Make a 'C' string."""

    if isinstance(string, bytes):
        try:
            _utf_8_decode(string, None, True)
            return string + b"\x00"
        except UnicodeError:
            raise InvalidStringData("strings in documents must be valid "
                                    "UTF-8: %r" % string)
    else:
        return _utf_8_encode(string)[0] + b"\x00"