code: function getCurrentFileSize(counter, timeout, cb) {
    var fd = fs.openSync(__filename, 'r');
  
    console.log("Trying to aquire lock for the %s time", counter);
  
    fs.flock(fd, 'exnb', function(err) {
      if (err) {
        return console.log("Couldn't lock file", counter);
      }
  
      console.log('Aquired lock', counter);
  
      // unlock after `timeout`
      setTimeout(function() {
        fs.flock(fd, 'un', function(err) {
          if (err) {
            return console.log("Couldn't unlock file", counter);
          }
  
          if (cb) { cb(); }
        });
      }, timeout);
    });
  }
docs: Function that locks the current file
  for `timeout` miliseconds
  
  The `counter` represents an index of how many
  times the function has been called so far
  (it acts as an id)
  
  The callback `cb` is optional