docs: def get_concrete_model(model):
      """ Get model defined in Meta.
  
      :param str or django.db.models.Model model:
      :return: model or None
      :rtype django.db.models.Model or None:
      :raise ValueError: model is not found or abstract
  
      """
      if not(inspect.isclass(model) and issubclass(model, models.Model)):
          model = get_model_by_name(model)
  
      return model