returns

List

example

import {L} from 'ts-toolbelt'

type test0 = L.Append<[1, 2, 3], 4> // [1, 2, 3, 4]
type test1 = L.Append<[], 'a'> // ['a']
type test2 = L.Append<readonly ['a', 'b'], 'c'> // ['a', 'b', 'c']
type test3 = L.Append<[1, 2], [3, 4]> // [1, 2, [3, 4]]