code: def _load(
      filename: Text, language: Optional[Text] = "en"
  ) -> Optional["TrainingData"]:
      """Loads a single training data file from disk."""
      fformat = guess_format(filename)
      if fformat == UNK:
          raise ValueError(
              f"Unknown data format for file '{filename}'."
          )
  
      reader = _reader_factory(fformat)
  
      if reader:
          return reader.read(
              filename, language=language, fformat=fformat
          )
      else:
          return None
  
file_path: rasa/rasa/shared/nlu/training_data/loading.py
imports: import json
  import logging
  import os
  import typing
  from typing import Optional, Text, Callable, Dict, Any, List
  import rasa.shared.utils.io
  from rasa.shared.nlu.training_data.formats.dialogflow import DIALOGFLOW_AGENT, DIALOGFLOW_ENTITIES, DIALOGFLOW_ENTITY_ENTRIES, DIALOGFLOW_INTENT, DIALOGFLOW_INTENT_EXAMPLES, DIALOGFLOW_PACKAGE
  from rasa.shared.nlu.training_data.training_data import TrainingData
label_desc: Use image node_id 3 for calling a global function with example usage: _load(filename, language) and returns: reader, None