code: func (r FutureGetNetworkHashPS) Receive() (int64, error) {
  	res, err := receiveFuture(r)
  	if err != nil {
  		return -1, err
  	}
  
  	// Unmarshal result as an int64.
  	var result int64
  	err = json.Unmarshal(res, &result)
  	if err != nil {
  		return 0, err
  	}
  
  	return result, nil
  }
docs: // Receive waits for the response promised by the future and returns the
  // estimated network hashes per second for the block heights provided by the
  // parameters.