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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 _prefix_from_prefix_int(self, prefixlen):
 """Validate and return a prefix length integer. Args: prefixlen: An integer containing the prefix length. Returns: The input, possibly converted from long to int. Raises: NetmaskValueError: If the input is not an integer, or out of range. """

        if not isinstance(prefixlen, (int, long)):
            raise NetmaskValueError('%r is not an integer' % prefixlen)
        prefixlen = int(prefixlen)
        if not (0 <= prefixlen <= self._max_prefixlen):
            raise NetmaskValueError('%d is not a valid prefix length' %
                                    prefixlen)
        return prefixlen