code: def build_dataset(task):
      """Helper function to select and build dataset."""
  
      if task == "LAMBADA":
          return _build_lambada_dataset()
      if task == "WIKITEXT103":
          return _build_wikitext103_dataset()
  
      raise NotImplementedError(
          "dataset for {} task is not " "implemented.".format(task)
      )
  
imports: import json
  import math
  import numpy
  import torch
  from megatron import get_args
  from megatron import print_rank_0
  from megatron import get_tokenizer
  from .detokenizer import get_detokenizer
label_desc: Use image node_id 1 for calling a global function with example usage: build_dataset(task) and returns: _build_lambada_dataset, _build_wikitext103_dataset