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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 getRealInterfaceNumber(self, interface):
 """ Returns the host-visible interface number, or None if there is no such interface. """

        try:
            return self._ioctl(INTERFACE_REVMAP, interface)
        except IOError as exc:
            if exc.errno == errno.EDOM:
                return None
            raise