code: function stringToFcntlFlags(flag) {
    if (typeof flag !== 'string') {
      return flag;
    }
  
    switch (flag) {
      case 'getfd':
        return binding.F_GETFD;
  
      case 'setfd':
        return binding.F_SETFD;
  
      case 'setlk':
        return binding.F_SETLK;
  
      case 'setlkw':
        return binding.F_SETLKW;
  
      case 'getlk':
        return binding.F_GETLK;
  
      default:
        throw new Error('Unknown fcntl flag: ' + flag);
    }
  }
docs: used by Fcntl