code: func (tab *Table) bucket(id enode.ID) *bucket {
  	d := enode.LogDist(tab.self().ID(), id)
  	if d <= bucketMinDistance {
  		return tab.buckets[0]
  	}
  	return tab.buckets[d-bucketMinDistance-1]
  }
docs: // bucket returns the bucket for the given node ID hash.