code: func (immutable *Immutable) Delete(entries ...Entry) (*Immutable, Entries) {
  	if len(entries) == 0 {
  		return immutable, Entries{}
  	}
  
  	deleted := make(Entries, 0, len(entries))
  	cp := immutable.copy()
  	for _, e := range entries {
  		deleted = append(deleted, cp.delete(e))
  	}
  
  	return cp, deleted
  }
docs: // Delete will remove the provided entries from this AVL tree and
  // return a new tree and any entries removed.  If an entry could not
  // be found, nil is returned in its place.