text: from typing import Dict
  
  
  class Customer:
      def __init__(self, customer_id: int, first_name: str, last_name: str, user_name: str):
          self.customer_id = customer_id
          self.first_name = first_name
          self.last_name = last_name
          self.user_name = user_name
  
      def make_customer_dictionary(self):
          return {
              "customerId": self.customer_id,
              "firstName": self.first_name,
              "lastName": self.last_name,
              "userName": self.user_name
          }
  
      def __str__(self):
          return "customer ID: {}, first name: {}, last name: {}, username: {}"\
              .format(self.customer_id, self.first_name, self.last_name, self.user_name)
  