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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 close(self):
        ''' terminate the connection '''
        cache_key = self._cache_key()
        SSH_CONNECTION_CACHE.pop(cache_key, None)
        SFTP_CONNECTION_CACHE.pop(cache_key, None)
        if self.sftp is not None:
            self.sftp.close()
        self.ssh.close()