code: def _check_categorical_option_type(option_name, option_value, possible_values):
      
      err_msg = '{0} is not a valid option for {1}. '.format(option_value, option_name)
      err_msg += ' Expected one of: '.format(possible_values)
  
      err_msg += ', '.join(map(str, possible_values))
      if option_value not in possible_values:
          raise ToolkitError(err_msg)
docs: Check whether or not the requested option is one of the allowed values.