code: def _get_sample(self, idx):
      np_gen = np.random.default_rng(seed=(self.seed + idx))
      sample = np_gen.integers(
          self.vocab_size, size=[self.max_seq_length], dtype=np.int64
      )
      return [sample], self.max_seq_length
  
imports: import collections
  import os
  import numpy
  import torch
  from nemo.collections.common.tokenizers import SentencePieceTokenizer, YouTokenToMeTokenizer
  from nemo.collections.nlp.data.language_modeling.megatron.dataset_utils import create_masked_lm_predictions, get_samples_mapping
  from nemo.collections.nlp.data.language_modeling.megatron.gpt_dataset import _build_index_mappings
  from nemo.core import Dataset
label_desc: Use image node_id 3 for calling the MockT5Dataset obj's underlying member method code with example usage: obj._get_sample(idx) and returns: list,  self