code: def testIndexing(self):
      layout = Layout([(0, 0, 1), (0, 1, 0), (1, 0, 0), (2, 1, 3)])
      self.assertEqual(len(layout), 4)
      self.assertEqual(layout[1], [0, 1, 0])
      self.assertEqual(layout[3], [2, 1, 3])
  
      row = layout[2]
      row[2] = 1
      self.assertEqual(layout[2], [1, 0, 1])
  
      del layout[1]
      self.assertEqual(len(layout), 3)
  
imports: import unittest
  from math import hypot
  from igraph import Graph, Layout, BoundingBox, InternalError
  from igraph import umap_compute_weights
label_desc: Use image node_id 2 for calling the LayoutTests obj's underlying member method code with example usage: obj.testIndexing() without return types