code: func (a *MinMaxAllocator) Release(i int) error {
  	a.lock.Lock()
  	defer a.lock.Unlock()
  
  	if !a.has(i) {
  		return nil
  	}
  
  	delete(a.used, i)
  
  	if a.inRange(i) {
  		a.free++
  	}
  
  	return nil
  }
docs: //Release free/delete provided value from the allocator.