code: def test_two_sheets_error(self, n_points):
      if self.space.n != self.space.p:
          raise ValueError("Test only defined for n=p.")
  
      point = self.space.random_point(n_points)
      base_point = self.space.random_point(n_points)
  
      det_point = gs.linalg.det(point)
      det_base = gs.linalg.det(base_point)
      if n_points > 1:
          for index in range(n_points):
              if (det_base[index] * det_point[index]) > 0.0:
                  point[index][0, :] *= -1
      else:
          if (det_base * det_point) > 0.0:
              point[0, :] *= -1.0
  
      with pytest.raises(ValueError):
          self.space.metric.log(point, base_point)
  
imports: import pytest
  import geomstats.backend
  from geomstats.geometry.grassmannian import Grassmannian
  from geomstats.test.test_case import TestCase
  from geomstats.test.vectorization import generate_vectorization_data
  from geomstats.test_cases.geometry.base import LevelSetTestCase
  from geomstats.test_cases.geometry.riemannian_metric import RiemannianMetricTestCase
label_desc: Use image node_id 7 for calling the StiefelCanonicalMetricTestCase obj's underlying member method code with example usage: obj.test_two_sheets_error(n_points) without return types