code: def test_plot_ggtitle():
      plot = gg.ggplot()
      ggtitle = gg.labs(title="New plot title")
  
      expect = {
          "ggtitle": {"text": "New plot title"},
          "kind": "plot",
          "data_meta": {},
          "layers": [],
          "mapping": {},
          "scales": [],
          "metainfo_list": [],
      }
  
      assert (plot + ggtitle).as_dict() == expect
  
file_path: lets-plot/python-package/test/plot/test_assembly.py
imports: import lets_plot
  from lets_plot.plot.core import DummySpec, FeatureSpecArray
  from lets_plot.plot.core import FeatureSpec
  from lets_plot.plot.core import LayerSpec
  from lets_plot.plot.geom import _geom
  from lets_plot.plot.scale import _scale
label_desc: Use image node_id 3 for calling a global function with example usage: test_plot_ggtitle() without return types