code: def __init__(
      self,
      init_token=None,
      eos_token=None,
      pad_token=None,
      unk_token=None,
  ):
      self.init_token = init_token
      self.eos_token = eos_token
      self.pad_token = pad_token
      self.unk_token = unk_token
      self.vocab_lst = []
      self.vocab_dict = None
  
file_path: dgl/examples/pytorch/transformer/dataset/fields.py
label_desc: Use image node_id 1 to create a new Vocab object  with example: obj = Vocab(init_token, eos_token, pad_token, unk_token)