class_docstr: Produces BERT inputs and answer spans for Squad.
class_docstr_tok: ["Produces","BERT","inputs","and","answer","spans","for","Squad","."]
code: def _lookup_tokens(self, text: str, seq_len: int = None):
      # BoS token is added explicitly in numberize(), -1 from max_seq_len
      max_seq_len = (seq_len or self.max_seq_len) - 1
      return lookup_tokens(
          text,
          tokenizer=self.tokenizer,
          vocab=self.vocab,
          bos_token=None,
          eos_token=self.vocab.eos_token,
          max_seq_len=max_seq_len,
      )
  
imports: import itertools
  from typing import List
  import torch
  from pytext.data.bert_tensorizer import BERTTensorizer
  from pytext.data.roberta_tensorizer import RoBERTaTensorizer
  from pytext.data.tensorizers import lookup_tokens
  from pytext.data.utils import pad_and_tensorize
  from pytext.torchscript.tensorizer import ScriptRoBERTaTensorizerWithIndices
  from pytext.torchscript.vocab import ScriptVocabulary
label_desc: Use image node_id 3 for calling the SquadForBERTTensorizer obj's underlying member method code with example usage: obj._lookup_tokens(text, seq_len) and returns: lookup_tokens