code: def _extract_answer(self, completion):
      match = ANS_RE.search(completion)
      if match:
          match_str = match.group(1).strip()
          match_str = match_str.replace(",", "")
          return match_str
      else:
          return INVALID_ANS
  
file_path: lm-evaluation-harness/lm_eval/tasks/gsm8k.py
imports: import re
  from lm_eval.base import Task, rf
  from lm_eval.metrics import mean
label_desc: Use image node_id 10 for calling the GradeSchoolMath8K obj's underlying member method code with example usage: obj._extract_answer(completion) and returns: match_str, INVALID_ANS