class NonEmptyArray2<A> {
    constructor(readonly first: A, readonly second: A, readonly tail: ReadonlyArray<A>) {}

    toArray(): A[] {
        return [this.first, this.second, ...this.tail];
    }
}

class xD<A> {
    constructor(readonly first: A, readonly second: A, readonly tail: ReadonlyArray<A>) { }

    toArray(): A[] {
        return [this.first];
    }
}

function needToAccessTwoItemsFunction(youShouldBeHappy: NonEmptyArray2<number>): void {
    const array = youShouldBeHappy.toArray();
    console.log(array[0]);
    console.log(array[1]);
}

needToAccessTwoItemsFunction(new NonEmptyArray2<number>(1, 2, []));
needToAccessTwoItemsFunction(new xD<number>(1, 2, []));