text: BERT_S_CASED_URL = "https://tfhub.dev/google/bert_cased_L-12_H-768_A-12/1"
  BERT_L_CASED_URL = "https://tfhub.dev/google/bert_cased_L-24_H-1024_A-16/1"
  
  BERT_CLS = "[CLS]"  # classification embedding token
  BERT_SEP = "[SEP]"  # sentence separator token for sentence pair tasks
  BERT_SUBLABEL = "X"  # ignore label used for subtokens
  