def METHOD_NAME(
    self, cost_category_arn: str
) -> CostCategoryDefinition:
    """
    The EffectiveOn-parameter is not yet implemented
    """
    if cost_category_arn not in self.cost_categories:
        ccd_id = cost_category_arn.split("/")[-1]
        raise CostCategoryNotFound(ccd_id)
    return self.cost_categories[cost_category_arn]