code: func (r FutureGetWork) Receive() (*btcjson.GetWorkResult, error) {
  	res, err := receiveFuture(r)
  	if err != nil {
  		return nil, err
  	}
  
  	// Unmarshal result as a getwork result object.
  	var result btcjson.GetWorkResult
  	err = json.Unmarshal(res, &result)
  	if err != nil {
  		return nil, err
  	}
  
  	return &result, nil
  }
docs: // Receive waits for the response promised by the future and returns the hash
  // data to work on.