method HashMapCollisionBuilder.prototype.modifyAtimport { HashMapCollisionBuilder } from "https://deno.land/x/rimbu@1.0.0/hashed/map-custom/index.ts"; modifyAt(atKey: K, options: { ifNew?: OptLazyOr<V, Token>; ifExists?: (currentEntry: V, remove: Token) => V | Token; }): booleanParametersatKey: Koptions: { ifNew?: OptLazyOr<V, Token>; ifExists?: (currentEntry: V, remove: Token) => V | Token; }Returnsboolean