// as long as you don't access the by-numeral-index functions,
// you can add and remove elements quickly.
// upon accessing the list, it is updated once to fit the new data
sclass ProbabilisticList<A> extends AbstractRandomAccessList<A> {
  MultiSetMap<Double, A> byProbability = multiSetMap_outerDescTreeMap_innerLinkedHashSet(); // main data structure
  L<> renderedAsList; // this is only updated when requested
}