code: func (ch *Ch) CheckingListen(ctx context.Context, cancelAll context.CancelFunc, totalActiveProcs int) (size uint, e error) {
  	ContentLens := uint(0)
  	for i := 0; i < totalActiveProcs; i++ {
  		select {
  		case <-ctx.Done():
  			i--
  		case err := <-ch.Err:
  			if e != nil {
  				cancelAll()
  			}
  			e = err
  		case size = <-ch.Size:
  			if ContentLens == 0 {
  				ContentLens = size
  			} else {
  				if ContentLens != size {
  					if e != nil {
  						cancelAll()
  					}
  					e = errors.New("Not match the file on each mirrors")
  				}
  			}
  		}
  	}
  
  	return
  }
docs: // CheckingListen method wait all channels for Checking method in requests