import { type Tuple } from "https://deno.land/x/ts_toolbelt_unofficial@1.1.0/mod.ts";
const { Merge } = Tuple;
Accurately merge the fields of L with the ones of L1. It is
equivalent to the spread operator in JavaScript. [[Union]]s and [[Optional]]
fields will be handled gracefully.
(⚠️ needs --strictNullChecks enabled)