code: def algebra_useful_matrix(theta, elem_33=0.0):
      return gs.array(
          [[0.0, -theta, 2.0], [theta, 0.0, 3.0], [0.0, 0.0, elem_33]]
      )
  
imports: import geomstats.backend
  from geomstats.test.data import TestData
  from .base import LevelSetTestData
  from .invariant_metric import InvariantMetricMatrixTestData
  from .lie_group import LieGroupTestData, MatrixLieGroupTestData
  from .mixins import ProjectionMixinsTestData
label_desc: Use image node_id 2 for calling a global function with example usage: algebra_useful_matrix(theta, elem_33) and returns: gs