code: func (e *podEnv) netPluginAdd(n *activeNet, netns string) error {
  	output, err := e.execNetPlugin("ADD", n, netns)
  	if err != nil {
  		return pluginErr(err, output)
  	}
  
  	pr := cnitypes.Result{}
  	if err = json.Unmarshal(output, &pr); err != nil {
  		err = errwrap.Wrap(fmt.Errorf("parsing %q", string(output)), err)
  		return errwrap.Wrap(fmt.Errorf("error parsing %q result", n.conf.Name), err)
  	}
  
  	if pr.IP4 == nil {
  		return nil // TODO(casey) should this be an error?
  	}
  
  	// All is well - mutate the runtime
  	n.runtime.MergeCNIResult(pr)
  	return nil
  }
docs: // Executes a given network plugin. If successful, mutates n.runtime with
  // the runtime information