code: func (fr *fileReader) reset() {
  	if fr.err != nil {
  		return
  	}
  	if fr.rc != nil {
  		fr.rc.Close()
  		fr.rc = nil
  	}
  }
docs: // resetReader resets the reader, forcing the read method to open up a new
  // connection and rebuild the buffered reader. This should be called when the
  // offset and the reader will become out of sync, such as during a seek
  // operation.