code: def _file_exists(bucket, directory, filename):
      file_blob = _get_blob(bucket, directory, filename)
      return gcs_join(directory, filename) == file_blob.name
  
imports: import pytest
  import datetime
  import os
  import json
  from sacred.observers import GoogleCloudStorageObserver
label_desc: Use image node_id 7 for calling a global function with example usage: _file_exists(bucket, directory, filename) and returns: unknown