add an item to the start of a tuple.
type Result1 = Prepend<[2, 3], 1>; // [1, 2, 3]type Result2 = Prepend<[], 1>; // [1] Copy
type Result1 = Prepend<[2, 3], 1>; // [1, 2, 3]type Result2 = Prepend<[], 1>; // [1]
add an item to the start of a tuple.