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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 remove_prefix(self, prefix):
 """Removes prefix from this set. This is a no-op if the prefix doesn't exist in it. """

        if prefix not in self.__prefix_map:
            return

        ni = self.__lookup_prefix(prefix)
        ni.prefixes.discard(prefix)
        del self.__prefix_map[prefix]

        # If we removed the preferred prefix, find a new one.
        if ni.preferred_prefix == prefix:
            ni.preferred_prefix = next(iter(ni.prefixes), None)