class_docstr: Full Wikipedia teacher that splits the chunks into train/valid/test.
class_docstr_tok: ["Full","Wikipedia","teacher","that","splits","the","chunks","into","train\/valid\/test","."]
code: def _set_chunk_idx_to_file(self):
      folder = self._get_data_folder()
      all_subdirs = sorted(
          [x for x in os.listdir(folder) if "README" not in x]
      )
      self.chunk_idx_to_file = {i: x for i, x in enumerate(all_subdirs)}
  
imports: from parlai.core.teachers import DialogTeacher, ChunkTeacher, ChunkOutput
  from parlai.utils.io import PathManager
  from parlai.core.message import Message
  from .build import build
  import json
  import os
  from typing import List, Tuple
label_desc: Use image node_id 4 for calling the FullSplitTeacher obj's underlying member method code with example usage: obj._set_chunk_idx_to_file() without return types