code: func (bucket *kbucket) Insert(no *node) bool {
  	isNew := !bucket.nodes.HasKey(no.id.RawString())
  
  	bucket.nodes.Push(no.id.RawString(), no)
  	bucket.UpdateTimestamp()
  
  	return isNew
  }
docs: // Insert inserts node to the bucket. It returns whether the node is new in
  // the bucket.