code: func HandleRead(req *ReadRequest, resp *ReadResponse, data []byte) {
  	if req.Offset >= int64(len(data)) {
  		data = nil
  	} else {
  		data = data[req.Offset:]
  	}
  	if len(data) > req.Size {
  		data = data[:req.Size]
  	}
  	n := copy(resp.Data[:req.Size], data)
  	resp.Data = resp.Data[:n]
  }
docs: // HandleRead handles a read request assuming that data is the entire file content.
  // It adjusts the amount returned in resp according to req.Offset and req.Size.