def personal_unlockAccount(self, address, passphrase=None, duration=None):
        """https://github.com/ethereum/go-ethereum/wiki/Management-APIs#personal_unlockaccount

        :param address: Account address
        :type address: str

        :param passphrase: Passphrase of account (optional)
        :type passphrase: str

        :param duration: Duration to be unlocked (optional)
        :type duration: int

        :rtype: bool
        """
        return (yield from self.rpc_call('personal_unlockAccount',
                                         [address, passphrase, duration]))