code: func (e *edit) Append(b []byte) error {
  	_, err := e.file.Seek(0, os.SEEK_END)
  	if err != nil {
  		return err
  	}
  
  	_, err = e.file.Write(b)
  	return err
  }
docs: // Append writes len(b) bytes at the end of the File. It returns an error, if any.