import { StreamBase } from "https://deno.land/x/rimbu@1.0.2/stream/custom/index.ts";
Parameters
flatMapFun: () => StreamSource<T2>
value: T,
index: number,
halt: () => void,
import { StreamBase } from "https://deno.land/x/rimbu@1.0.2/stream/custom/index.ts";