code: def doc_to_target(self, doc):
      return " " + self.get_answer_option(self.last_problem(doc))
  
imports: import collections
  import datasets
  import numpy
  from lm_eval.base import rf, Task
  from lm_eval.metrics import mean
label_desc: Use image node_id 13 for calling the RACE obj's underlying member method code with example usage: obj.doc_to_target(doc) and returns: unknown