import { type NullableKeys } from "https://deno.land/x/itertools@v1.1.1/types.ts";
definition: [K in keyof T]-?: IsNullable<T[K], K>[keyof T]
x/itertools/types.ts>NullableKeys
import { type NullableKeys } from "https://deno.land/x/itertools@v1.1.1/types.ts";