code: def dataset_dest_prefix(args, output_prefix, lang):
      base = os.path.join(args.destdir, output_prefix)
      if lang is not None:
          lang_part = f".{args.source_lang}-{args.target_lang}.{lang}"
      elif args.only_source:
          lang_part = ""
      else:
          lang_part = f".{args.source_lang}-{args.target_lang}"
  
      return "{}{}".format(base, lang_part)
  
imports: import logging
  import os
  import shutil
  import sys
  import typing
  from argparse import Namespace
  from itertools import zip_longest
  from fairseq import options, tasks, utils
  from fairseq.binarizer import AlignmentDatasetBinarizer, FileBinarizer, VocabularyDatasetBinarizer
  from fairseq.data import Dictionary
label_desc: Use image node_id 5 for calling a global function with example usage: dataset_dest_prefix(args, output_prefix, lang) and returns: str