function jobStarted(
    bytes16 _jobId,
    address _hirer,
    address _contractor,
    uint256 _value,
    uint256 _fee
  ) external onlyContractor(_contractor)
  {
    
    bytes32 jobHash = getJobHash(
      _jobId,
      _hirer,
      _contractor,
      _value,
      _fee);

    
    require(jobEscrows[jobHash].exists);
    
    require(jobEscrows[jobHash].status == STATUS_JOB_CREATED);
    jobEscrows[jobHash].status = STATUS_JOB_STARTED; 
    jobEscrows[jobHash].hirerCanCancelAfter = 0;
    jobEscrows[jobHash].agreedCompletionDate = uint32(block.timestamp) + jobEscrows[jobHash].secondsToComplete;
    emit ContractorStartedJob(jobHash, msg.sender);
  }