class_docstr: Wrapper class for data config YAML
class_docstr_tok: ["Wrapper","class","for","data","config","YAML"]
docstr: fairseq vocabulary file under data root
docstr_tok: ["fairseq","vocabulary","file","under","data","root"]
code: def vocab_filename(self):
      """fairseq vocabulary file under data root"""
      return self.config.get("vocab_filename", "dict.txt")
  
imports: import logging
  from argparse import Namespace
  from copy import deepcopy
  from pathlib import Path
  from typing import Dict, Optional
  from fairseq.data import Dictionary
label_desc: Use image node_id 3 for calling the S2TDataConfig obj's underlying member method code with example usage: obj.vocab_filename() and returns: self