def sign(self, id, transaction, otp):
        """
        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param transaction: the hex encoded [partially signed] compact transaction to sign
        :param otp: the one time password
        """
        payload = {
            'otp': otp,
            'transaction': transaction
        }
        return self.send_request('post', 'cosigner/%s/sign' % quote(id), payload,
                                 timeout=60)

        Attempt to authenticate for a particular cosigner.
        :param id: the id of the cosigner
        :param transaction: the hex encoded [partially signed] compact transaction to sign
        :param otp: the one time password
        
electrum/plugins/trustedcoin/trustedcoin.py