code: def process_results(self, doc, results):
      (is_prediction,) = results
      return {"acc": is_prediction}
  
imports: from lm_eval.base import Task, rf
  from lm_eval.metrics import mean
label_desc: Use image node_id 12 for calling the Arithmetic obj's underlying member method code with example usage: obj.process_results(doc, results) and returns: dict