If

Implement the util type If<C, T, F> which accepts condition C, a truthy value T, and a falsy value F. C is expected to be either true or false while T and F can be any type.

For example:

type A = If<true, 'a', 'b'>  // expected to be 'a'
type B = If<false, 'a', 'b'> // expected to be 'b'