code: func (pq *GetUtxoRequestPQ) Pop() interface{} {
  	old := *pq
  	n := len(old)
  	item := old[n-1]
  	*pq = old[0 : n-1]
  	return item
  }
docs: // Pop is called by the heap.Interface implementation to remove an element from
  // the end of the backing store. The heap library will then maintain the heap
  // invariant.