code: func (r Response) Apply() error {
  	var req, opts, err = r.applyRequest()
  
  	if err != nil {
  		return err
  	}
  
  	return r.applyUpdate(req, opts)
  }
docs: // Apply performs an update of the current executable (or TargetFile, if it was
  // set on the Options) with the update specified by Response.
  //
  // Error is nil if and only if the entire update completes successfully.