code: def numberize(self, row: Dict):
      return row["num_negative_ctx"]
  
imports: from typing import Any, Dict, List, Optional, Tuple
  from pytext.common.constants import SpecialTokens
  from pytext.config.component import ComponentType, create_component
  from pytext.data.bert_tensorizer import BERTTensorizer, build_fairseq_vocab
  from pytext.data.roberta_tensorizer import RoBERTaTensorizer
  from pytext.data.tensorizers import LabelTensorizer
  from pytext.data.tokenizers import Tokenizer
  from pytext.data.utils import Vocabulary
  from pytext.utils.file_io import PathManager
label_desc: Use image node_id 1 for calling the PositiveLabelTensorizerForDenseRetrieval obj's underlying member method code with example usage: obj.numberize(row) and returns: row