function tree.foldimport { tree } from "https://deno.land/x/fun@v2.0.0/mod.ts"; const { fold } = tree; fold<A, O>(foao: (o: O, a: A) => O, o: O): (ta: Tree<A>) => OThe fold function for Foldable. Type ParametersAOParametersfoao: (o: O, a: A) => Oo: OReturns(ta: Tree<A>) => O