type alias T.Nullableimport { type T } from "https://deno.land/x/ts_toolbelt_unofficial@1.1.0/mod.ts"; const { Nullable } = T; Make some entries of L nullable (deeply or not) ExamplesExample 1 Type ParametersL extends ListoptionalK extends Key = Keydefinition: Cast<Update<L, `${K & number}` | K, x | null | undefined>, List>