code: func (r *Request) SkipPeer(nodeID string) bool {
  	val, ok := r.peersToSkip.Load(nodeID)
  	if !ok {
  		return false
  	}
  	t, ok := val.(time.Time)
  	if ok && time.Now().After(t.Add(RequestTimeout)) {
  		// deadline expired
  		r.peersToSkip.Delete(nodeID)
  		return false
  	}
  	return true
  }
docs: // SkipPeer returns if the peer with nodeID should not be requested to deliver a chunk.
  // Peers to skip are kept per Request and for a time period of RequestTimeout.
  // This function is used in stream package in Delivery.RequestFromPeers to optimize
  // requests for chunks.