phfi(...);

const business = graph.bookingBusinesses.getById({Booking Business Id})();
// get the business customers
const customers = await business.customers();
// add a customer
const newCustomerDesc: BookingCustomer = {booking customer details -- see Microsoft Graph documentation};
const newCustomer = customers.add(newCustomerDesc);
// get customer by id
const customer = await business.customers.getById({customer id})();
// update customer
const updateCustomerDesc: BookingCustomer = {booking customer de