import { Collection } from "https://deno.land/x/collection@v1.0.1/src/Collection.ts";
Maps each item into a Collection, then joins the results into a single Collection. Identical in behavior to Array.flatMap().
Examples
collection.flatMap(guild => guild.members.cache);
collection.flatMap(guild => guild.members.cache);
Parameters
fn: () => Collection<K, T>
value: V,
key: K,
collection: this,
Function that produces a new Collection
Returns
Collection<K, T>