code: def test_quadmesh_to_trimesh(self):
      qmesh = QuadMesh(([0, 1], [0, 1], np.array([[0, 1], [2, 3]])))
      trimesh = qmesh.trimesh()
      simplices = np.array(
          [
              [0, 1, 3, 0],
              [1, 2, 4, 2],
              [3, 4, 6, 1],
              [4, 5, 7, 3],
              [4, 3, 1, 0],
              [5, 4, 2, 2],
              [7, 6, 4, 1],
              [8, 7, 5, 3],
          ]
      )
      vertices = np.array(
          [
              (-0.5, -0.5),
              (-0.5, 0.5),
              (-0.5, 1.5),
              (0.5, -0.5),
              (0.5, 0.5),
              (0.5, 1.5),
              (1.5, -0.5),
              (1.5, 0.5),
              (1.5, 1.5),
          ]
      )
      self.assertEqual(trimesh.array(), simplices)
      self.assertEqual(trimesh.nodes.array([0, 1]), vertices)
  
imports: import numpy
  from holoviews.element import HSV, RGB, Curve, Image, QuadMesh, Raster
  from holoviews.element.comparison import ComparisonTestCase
label_desc: Use image node_id 3 for calling the TestQuadMesh obj's underlying member method code with example usage: obj.test_quadmesh_to_trimesh() without return types