public List <Customer> InvitedCustomers()
        {
            var invitationList = new List <Customer>();
            var customers      = new Customer();
            var distance       = new Distance();

            try
            {
                foreach (var customer in customers.GetCustomerList(_file))
                {
                    var customerDistance = distance.CalculateDistance(_destination, customer);
                    if (customerDistance <= _maxDistance)
                    {
                        invitationList.Add(customer);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                throw;
            }
            return(invitationList);
        }