code: func (w *KeyedValue) Init(k string, v interface{}) {
  	w.lock.Lock()
  	defer w.lock.Unlock()
  
  	// If we have a waiter, set the value.
  	_, val := w.valueWaiter(k)
  	if val != nil {
  		w.setValue(k, v)
  	}
  }
docs: // Init will initialize the key to a given value only if the key has
  // not been set before. This is safe to call multiple times and in parallel.