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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_entry(self, source_file, key):
 """Remove an entry from the cache. source_file is the name of the header and key is its corresponding cache key (obtained by a call to :meth:_create_cache_key ). The entry is removed from the index table, any referenced file name is released and the cache file is deleted. If key references a non-existing entry, the method returns immediately. :param source_file: Header file name :type source_file: str :param key: Key value for the specified header file :type key: hash table object """


        entry = self.__index.get(key)
        if entry is None:
            return

        # Release the referenced files...
        for id_, _ in entry.filesigs:
            self.__filename_rep.release_filename(id_)

        # Remove the cache entry...
        del self.__index[key]
        self.__modified_flag = True

        # Delete the corresponding cache file...
        cachefilename = self._create_cache_filename(source_file)
        try:
            os.remove(cachefilename)
        except OSError as e:
            print("Could not remove cache file (%s)" % e)