code: def test_nested_attr(self):
      assert self.scatter.marker.colorbar.titlefont.family is None
      self.scatter.marker.colorbar.titlefont.family = "courier"
      assert self.scatter.marker.colorbar.titlefont.family == "courier"
      d1, d2 = strip_dict_params(self.scatter, self.expected_nested)
      assert d1 == d2
  
imports: from unittest import TestCase
  import plotly.graph_objs
  from plotly.tests.utils import strip_dict_params
label_desc: Use image node_id 4 for calling the TestAssignmentPrimitive obj's underlying member method code with example usage: obj.test_nested_attr() without return types