code: func (s *Store) MakePrivateCollection(compare KeyCompare) *Collection {
  	if compare == nil {
  		compare = bytes.Compare
  	}
  	return &Collection{
  		store:    s,
  		compare:  compare,
  		rootLock: &sync.Mutex{},
  		root:     &rootNodeLoc{refs: 1, root: empty_nodeLoc},
  	}
  }
docs: // Returns a new, unregistered (non-named) collection.  This allows
  // advanced users to manage collections of private collections.