code: func (h *Heap) List() []interface{} {
  	h.lock.RLock()
  	defer h.lock.RUnlock()
  	list := make([]interface{}, 0, len(h.data.items))
  	for _, item := range h.data.items {
  		list = append(list, item.obj)
  	}
  	return list
  }
docs: // List returns a list of all the items.