code: func logPanic(r interface{}) {
  	callers := ""
  	for i := 0; true; i++ {
  		_, file, line, ok := runtime.Caller(i)
  		if !ok {
  			break
  		}
  		callers = callers + fmt.Sprintf("%v:%v\n", file, line)
  	}
  	glog.Errorf("Recovered from panic: %#v (%v)\n%v", r, r, callers)
  }
docs: // logPanic logs the caller tree when a panic occurs.