code: def test_optional_import_nonexisting():
      has_nonex, nonex = optional_import("clearlynonexistingpackage")
      assert not has_nonex
      assert nonex is None
  
imports: import pytest
  from sacred.optional import optional_import, get_tensorflow, modules_exist
label_desc: Use image node_id 2 for calling a global function with example usage: test_optional_import_nonexisting() without return types