code: def test_assign_toplevel_array(self):
      self.assertEqual(self.parcoords.dimensions, ())
  
      self.parcoords["dimensions"] = [
          go.parcoords.Dimension(values=[2, 3, 1], visible=True),
          dict(values=[1, 2, 3], label="dim1"),
      ]
  
      self.assertEqual(
          self.parcoords.to_plotly_json(), self.expected_toplevel
      )
  
imports: from unittest import TestCase
  import plotly.graph_objs
  from plotly.tests.utils import strip_dict_params
label_desc: Use image node_id 2 for calling the TestAssignCompoundArray obj's underlying member method code with example usage: obj.test_assign_toplevel_array() without return types