function claim(
      address _arbitrator,
      uint256 _transactionId
  ) public {
    Lock memory lock = escrows[_arbitrator][_transactionId];

    require(lock.sender == msg.sender);
    require(lock.paid);
    require(lock.expiration < block.timestamp);
    require(lock.expiration != 0);
    require(lock.expiration != 1);

    delete escrows[_arbitrator][_transactionId];

    token.transfer(msg.sender, lock.value.add(lock.fee));

    Released(
      _arbitrator,
      msg.sender,
      _transactionId
    );
  }