code: def test_add_traces(self):
      # Add two traces
      self.figure.add_traces(
          [
              go.Sankey(arrangement="snap"),
              go.Histogram2dContour(line={"color": "cyan"}),
          ]
      )
  
      # Check access properties
      self.assertEqual(self.figure.data[-2].type, "sankey")
      self.assertEqual(self.figure.data[-2].arrangement, "snap")
  
      self.assertEqual(self.figure.data[-1].type, "histogram2dcontour")
      self.assertEqual(self.figure.data[-1].line.color, "cyan")
  
      # Check message
      new_uid1 = self.figure.data[-2].uid
      new_uid2 = self.figure.data[-1].uid
      self.figure._send_addTraces_msg.assert_called_once_with(
          [
              {"type": "sankey", "arrangement": "snap"},
              {"type": "histogram2dcontour", "line": {"color": "cyan"}},
          ]
      )
  
file_path: plotly.py/packages/python/plotly/plotly/tests/test_core/test_figure_messages/test_add_traces.py
imports: import sys
  from unittest import TestCase
  import plotly.graph_objs
  from plotly.subplots import make_subplots
label_desc: Use image node_id 3 for calling the TestAddTracesMessage obj's underlying member method code with example usage: obj.test_add_traces() without return types