import { Deno } from "https://deno.land/x/deno@v1.30.0/cli/tsc/dts/lib.deno.unstable.d.ts";
const { UnsafeCallback } = Deno;
Removes one from this callback's reference counting and returns the new reference count.
If the callback's reference counter is zero, it will no longer keep Deno's process from exiting.