code: def test_snapshot_no_dependencies():
      response = RuntimeEnvironmentManager().snapshot(dependencies=None)
      assert response is None
  
imports: from __future__ import absolute_import
  import subprocess
  import pytest
  from mock import patch, Mock
  import sys
  import shlex
  import os
  from mock.mock import MagicMock
  from sagemaker.remote_function.runtime_environment.runtime_environment_manager import RuntimeEnvironmentManager, RuntimeEnvironmentError
label_desc: Use image node_id 1 for calling a global function with example usage: test_snapshot_no_dependencies() without return types