code: func (r *PortAllocator) Release(port int) error {
  	ok, offset := r.contains(port)
  	if !ok {
  		klog.Warningf("port is not in the range when release it. port: %v", port)
  		return nil
  	}
  
  	return r.alloc.Release(offset)
  }
docs: // Release releases the port back to the pool. Releasing an
  // unallocated port or a port out of the range is a no-op and
  // returns no error.