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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 release_filename(self, id_):
 """Release a file name. """


        entry = self.__entries.get(id_)
        if entry is None:
            raise ValueError("Invalid filename id (%d)" % id_)

        # Decrease reference count and check if the entry has to be removed...
        if entry.dec_ref_count() == 0:
            del self.__entries[id_]
            del self.__id_lut[entry.filename]