code: def _get_exception_class_from_status_code(status_code):
      
      if status_code == '100':
          return None
  
      exc_class = STATUS_CODE_MAPPING.get(status_code)
      if not exc_class:
          # No status code match, return the "I don't know wtf this is"
          # exception class.
          return STATUS_CODE_MAPPING['UNKNOWN']
      else:
          # Match found, yay.
          return exc_class
docs: Utility function that accepts a status code, and spits out a reference
      to the correct exception class to raise.
  
      :param str status_code: The status code to return an exception class for.
      :rtype: PetfinderAPIError or None
      :returns: The appropriate PetfinderAPIError subclass. If the status code
          is not an error, return ``None``.