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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 create_key(self, title, key):
 """Create a deploy key. :param str title: (required), title of key :param str key: (required), key text :returns: :class:`Key <github3.users.Key>` if successful, else None """

        json = None
        if title and key:
            data = {'title': title, 'key': key}
            url = self._build_url('keys', base_url=self._api)
            json = self._json(self._post(url, data=data), 201)
        return Key(json, self) if json else None