class_docstr: Task to finetune RoBERTa for Commonsense QA.
code: def build_model(self, args, from_checkpoint=False):
      from fairseq import models
  
      model = models.build_model(args, self)
  
      model.register_classification_head(
          "sentence_classification_head",
          num_classes=1,
      )
  
      return model
  
file_path: fairseq/examples/roberta/commonsense_qa/commonsense_qa_task.py
imports: import json
  import os
  import numpy
  import torch
  from fairseq.data import Dictionary, IdDataset, ListDataset, NestedDictionaryDataset, NumelDataset, NumSamplesDataset, RawLabelDataset, RightPadDataset, SortDataset, data_utils, encoders
  from fairseq.tasks import LegacyFairseqTask, register_task
label_desc: Use image node_id 6 for calling the CommonsenseQATask obj's underlying member method code with example usage: obj.build_model(args, from_checkpoint) and returns: model