code: def test_validate_assigned_traces_are_not_duplicates(self):
      traces = self.figure.data
      with pytest.raises(ValueError):
          self.figure.data = [traces[2], traces[1], traces[1]]
  
file_path: plotly.py/packages/python/plotly/plotly/tests/test_core/test_figure_messages/test_move_delete_traces.py
imports: import sys
  from unittest import TestCase
  import pytest
  import plotly.graph_objs
label_desc: Use image node_id 9 for calling the TestMoveDeleteTracesMessages obj's underlying member method code with example usage: obj.test_validate_assigned_traces_are_not_duplicates() without return types