code: def standardize_data_format(data_format):
      if data_format is None:
          return image_data_format()
      data_format = str(data_format).lower()
      if data_format not in {"channels_first", "channels_last"}:
          raise ValueError(
              "The `data_format` argument must be one of "
              "{'channels_first', 'channels_last'}. "
              f"Received: data_format={data_format}"
          )
      return data_format
  
file_path: keras/keras/backend/config.py
imports: import json
  import os
  from keras.api_export import keras_export
label_desc: Use image node_id 7 for calling a global function with example usage: standardize_data_format(data_format) and returns: data_format, image_data_format