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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 _ip_int_from_prefix(self, prefixlen=None):
 """Turn the prefix length netmask into a int for comparison. Args: prefixlen: An integer, the prefix length. Returns: An integer. """

        if prefixlen is None:
            prefixlen = self._prefixlen
        return self._ALL_ONES ^ (self._ALL_ONES >> prefixlen)