code: def retrieve(customer_id):
          
          http_client = HttpClient()
          response, __ = http_client.get(routes.url(routes.CUSTOMER_RESOURCE, resource_id=customer_id))
          return resources.Customer(**response)
docs: Retrieve a customer from its id.
  
          :param customer_id: The customer id
          :type customer_id: string
  
          :return: The customer resource
          :rtype: resources.Customer