code: func (file *LockFile) ReadPid() (pid int, err error) {
  	if _, err = file.Seek(0, os.SEEK_SET); err != nil {
  		return
  	}
  	_, err = fmt.Fscan(file, &pid)
  	return
  }
docs: // ReadPid reads process id from file and returns pid.
  // If unable read from a file, returns error.