code: def test_gggrid_theme():
      spec = gg.gggrid([gg.ggplot()]) + gg.theme_grey()
      assert "theme" in spec.as_dict()
      assert spec.as_dict()["theme"] == {"name": "grey"}
  
file_path: lets-plot/python-package/test/plot/test_gggrid_theme.py
imports: import lets_plot
  from lets_plot._global_settings import PLOT_THEME
label_desc: Use image node_id 1 for calling a global function with example usage: test_gggrid_theme() without return types