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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 is_unlocked(self):
 """``False`` if this is a private key that is protected with a passphrase and has not yet been unlocked, otherwise ``True``"""

        if self.is_public:
            return True

        if not self.is_protected:
            return True

        return self._key.unlocked