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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 _find_keys(self, identity='image'):
 """ Finds and returns all keys for identity, """

        prefix = add_prefix('', identity)
        raw_keys = self._find_keys_raw(prefix) or []
        for raw_key in raw_keys:
            yield del_prefix(raw_key)