code: func InterceptFunc(intc InterceptorFunc, when When, target interface{}) {
  	interceptors = append(interceptors, &Interception{
  		When:         when,
  		function:     intc,
  		callable:     reflect.ValueOf(intc),
  		target:       reflect.TypeOf(target),
  		interceptAll: target == AllControllers,
  	})
  }
docs: // InterceptFunc installs a general interceptor.
  // This can be applied to any Controller.
  // It must have the signature of:
  //   func example(c *revel.Controller) revel.Result