code: def basis_test_data(self):
      data = [
          dict(
              expected=gs.array(
                  [
                      [[1.0, 0.0], [0.0, 0.0]],
                      [[0.0, 0.0], [1.0, 0.0]],
                      [[0.0, 0.0], [0.0, 1.0]],
                  ]
              ),
          )
      ]
      return self.generate_tests(data)
  
file_path: geomstats/tests/tests_geomstats/test_geometry/data/lower_triangular_matrices.py
imports: import geomstats.backend
  from geomstats.test.data import TestData
  from .base import MatrixVectorSpaceTestData
label_desc: Use image node_id 3 for calling the LowerTriangularMatrices2TestData obj's underlying member method code with example usage: obj.basis_test_data() and returns: self