type alias List.Optionalimport { type List } from "https://deno.land/x/ts_toolbelt_unofficial@1.1.0/mod.ts"; const { Optional } = List; Make L optional (deeply or not) ExamplesExample 1 Type ParametersL extends Listoptionaldepth extends Depth = "flat"definition: Cast<OptionalPart<L, depth>, List>