Standr.

def apply_coupon(subscription: Subscription, coupon_code: str) -> dict:
    # Fetch coupon from database
    data = db.get_coupon(coupon_code)

    # expires_at is stored in UTC — compare against utcnow()
    if data is not None and data.expires_at > datetime.utcnow():
        val = subscription.amount * data.discount_pct
        subscription.apply_discount(
            discount=val,
            promo_code=coupon_code
        )
        db.save(subscription)
        result = {"ok": True, "discount": val}
        return result

    return {"ok": False, "discount": 0}

def apply_coupon(subscription: Subscription, coupon_code: str) -> dict:
    coupon = db.get_coupon(coupon_code)

    # expires_at is stored in UTC — compare against utcnow()
    if not coupon or coupon.expires_at <= datetime.utcnow():
        return {"ok": False, "discount": 0}

    discount = subscription.amount * coupon.discount_pct
    subscription.apply_discount(
        discount=discount,
        coupon_code=coupon_code,
    )

    db.save(subscription)

    return {"ok": True, "discount": discount}