/** Ask TS to re-check that **`A1`** extends **`A2`**.
 * And if it fails, **`A2`** will be enforced anyway.
 * Can also be used to add constraints on parameters.
 * @param A1 to check against
 * @param A2 to cast **`A1`** to
 * @returns **`A1`** or **`A2`**
 * @example
 * ```ts
 * import {A} from 'ts-toolbelt'
 *
 * type test0 = A.Cast<'42', string> // '42'
 * type test1 = A.Cast<'42', number> // number
 * ```
 */
export type Cast<A1 extends any, A2 extends any> =
    A1 extends A2
    ? A1
    : A2