code: def test_property_assignment_nested(self):
      self.figure.layout.xaxis.title.font.family = "courier"
      self.figure._send_relayout_msg.assert_called_once_with(
          {"xaxis.title.font.family": "courier"}
      )
  
file_path: plotly.py/packages/python/plotly/plotly/tests/test_core/test_figure_messages/test_plotly_relayout.py
imports: import sys
  from unittest import TestCase
  import plotly.graph_objs
label_desc: Use image node_id 3 for calling the TestRelayoutMessage obj's underlying member method code with example usage: obj.test_property_assignment_nested() without return types