code: def testCheckFilesystemSupport_fallback(self):
      with mock.patch.object(
          tf.io, "gfile", autospec=True
      ) as mock_gfile:
          del mock_gfile.get_registered_schemes
          with mock.patch(
              "builtins.__import__",
              side_effect=self.fake_import(
                  _TENSORFLOW_IO_MODULE, success=True
              ),
          ) as mock_import:
              mock_gfile.exists.return_value = True
              data_ingester._check_filesystem_support(
                  ["gs://bucket/abc"]
              )
      mock_import.assert_not_called()
      mock_gfile.exists.assert_called_once_with("gs://bucket/abc")
  
imports: import ntpath
  import os
  import posixpath
  import time
  from unittest import mock
  from tensorboard import test
  from tensorboard.backend.event_processing import data_ingester
  from tensorboard.compat import tf
label_desc: Use image node_id 6 for calling the FileSystemSupportTest obj's underlying member method code with example usage: obj.testCheckFilesystemSupport_fallback() without return types