code: func (f *DeltaFIFO) List() []interface{} {
  	f.lock.RLock()
  	defer f.lock.RUnlock()
  	return f.listLocked()
  }
docs: // List returns a list of all the items; it returns the object
  // from the most recent Delta.
  // You should treat the items returned inside the deltas as immutable.