text: class ClientError(Exception):
      """Response code between 400 and 499"""
      
  class ServerError(Exception):
      """Response code between 500 and 599"""
  
  class ServiceTicketValidationError(Exception):
      """An error caused when a ST is not valid for the specified service"""
  
  def raise_on_error(response):
      """Raises an appropriate exception if the response is an error"""
      if 400 <= response.status_code < 500:
          raise ClientError(response.text)
      if 500 <= response.status_code < 600:
          raise ServerError(response.text)
  