code: def test_add_trace_underscore_kwarg(self):
      fig = go.Figure()
  
      fig.add_scatter(y=[2, 1, 3], marker_line_color="green")
  
      self.assertEqual(fig.data[0].marker.line.color, "green")
  
imports: import plotly.graph_objects
  from plotly.subplots import make_subplots
  from plotly.tests.utils import TestCaseNoTemplate
  import pytest
label_desc: Use image node_id 11 for calling the FigureTest obj's underlying member method code with example usage: obj.test_add_trace_underscore_kwarg() without return types