async function createTiers(tiers) {
            /** @type {Object<string, MockedTier>} */
            const results = {};
            let i = 1;
            for (const tier of tiers) {
                await db('products').insert({id: tier});
                await db('stripe_products').insert({
                    product_id: tier,
                    stripe_product_id: `stripe_product_${tier}`
                });
                await db('stripe_prices').insert({
                    id: `stripe_price_month_${tier}`,
                    stripe_price_id: `stripe_price_month_${tier}`,
                    stripe_product_id: `stripe_product_${tier}`,
                    interval: 'month'
                });
                await db('stripe_prices').insert({
                    id: `stripe_price_year_${tier}`,
                    stripe_price_id: `stripe_price_year_${tier}`,
                    stripe_product_id: `stripe_product_${tier}`,
                    interval: 'year'
                });
                results[tier] = {
                    monthly: {
                        tier: tier,
                        cadence: 'month',
                        mrr: 100 * i
                    },
                    yearly: {
                        tier: tier,
                        cadence: 'year',
                        mrr: 80 * i
                    }
                };
                i += 1;
            }
            return results;
        }
@param {string[]} tiers
@returns {Promise<Object<string, MockedTier>>}