code: func (ff *FileFragment) Read(b []byte) (n int, err error) {
  	offset, err := ff.file.Seek(0, io.SeekCurrent)
  	if err != nil {
  		return 0, err
  	}
  
  	if int64(len(b)) > ff.endLoc-offset {
  		n, err := ff.file.Read(b[:ff.endLoc-offset])
  		if int64(n) == ff.endLoc-offset {
  			return n, io.EOF
  		}
  		return n, err
  	}
  	return ff.file.Read(b)
  }
docs: // Read implements io.Reader for FileFragment.