<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def generate_key(self):
 """ Ask mist.io to randomly generate a private ssh-key to be used with the creation of a new Key :returns: A string of a randomly generated ssh private key """

        req = self.request(self.uri + "/keys")
        private_key = req.post().json()
        return private_key['priv']