public IEnumerable<Customer> GetCustomersForAddress(IEnumerable<Customer> customers, Address address)
 {
     return customers.Where(c => c.Address != null && c.Address.Equals(address));
 }
 public Customer VerifyCustomerAddress(Customer customer, Address address)
 {
     return address != null && address.Equals(customer.Address) ? customer : null;
 }
 public Customer GetCustomerForAddress(IEnumerable<Customer> customers, Address address)
 {
     return customers.SingleOrDefault(c => c.Address != null && c.Address.Equals(address));
 }