code: def last_problem(cls, doc):
      return doc["problems"][-1]
  
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 9 for calling the RACE obj's underlying member method code with example usage: obj.last_problem(cls, doc) and returns: doc