class IteratorHelper implements Iterable<T>import { IteratorHelper } from "https://dotland.deno.dev/x/pg_mem@2.6.13/utils.ts"; ConstructorsnewIteratorHelper(underlying: () => Iterable<T>)Type ParametersTMethodsflatten(): T extends Iterable<infer X> ? IteratorHelper<X> : neverreduce<U>(callbackfn: (previousValue: U,currentValue: T,currentIndex: number,) => U, initialValue: U): U[Symbol.iterator]()