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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 unload(self, key):
 """ Unload a loaded key and its subkeys. The easiest way to do this is to select a key using :py:meth:`PGPKeyring.key` first:: with keyring.key("DSA von TestKey") as key: keyring.unload(key) :param key: The key to unload. :type key: :py:obj:`PGPKey` """

        assert isinstance(key, PGPKey)
        pkid = id(key)
        if pkid in self._keys:
            # remove references
            [ kd.remove(pkid) for kd in [self._pubkeys, self._privkeys] if pkid in kd ]
            # remove the key
            self._keys.pop(pkid)

            # remove aliases
            for m, a in [ (m, a) for m in self._aliases for a, p in m.items() if p == pkid ]:
                m.pop(a)
                # do a re-sort of this alias if it was not unique
                if a in self:
                    self._sort_alias(a)

            # if key is a primary key, unload its subkeys as well
            if key.is_primary:
                [ self.unload(sk) for sk in key.subkeys.values() ]