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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 clear(self) -> None: """ Clear all cache entries for directory and, if it is a 'pure' directory, remove the directory itself """

        if self._cache_directory is not None:
            # Safety - if there isn't a cache directory file, this probably isn't a valid cache
            assert os.path.exists(self._cache_directory_index), "Attempt to clear a non-existent cache"
            self._load()            # Shouldn't have any impact but...
            for e in self._cache.values():
                if os.path.exists(e.loc):
                    os.remove(e.loc)
            self._cache.clear()
            self._update()
        self._cache = {}