code: def test_stepsampler_variable_speed_SLOW(plot=False):
      matrices = [
          np.array(
              [
                  [True, True, True],
                  [False, True, True],
                  [False, False, True],
              ]
          ),
          [Ellipsis, slice(1, None), slice(2, 4)],
      ]
      for i, matrix in enumerate(matrices):
          np.random.seed(42 + i)
          sampler = ReactiveNestedSampler(
              paramnames, loglike, transform=transform
          )
          sampler.stepsampler = SpeedVariableRegionSliceSampler(matrix)
          r = sampler.run(log_interval=50, min_num_live_points=400)
          sampler.print_results()
          a = (np.abs(r["samples"] - 0.7) < 0.1).all(axis=1)
          b = (np.abs(r["samples"] - 0.3) < 0.1).all(axis=1)
          assert a.sum() > 1
          assert b.sum() > 1
  
imports: import numpy
  from ultranest.mlfriends import ScalingLayer, AffineLayer, MLFriends
  from ultranest import ReactiveNestedSampler
  from ultranest.stepsampler import RegionMHSampler, CubeMHSampler, CubeSliceSampler, RegionSliceSampler, SpeedVariableRegionSliceSampler, RegionBallSliceSampler
  from ultranest.stepsampler import generate_region_random_direction, ellipsoid_bracket, crop_bracket_at_unit_cube
  from ultranest.pathsampler import SamplingPathStepSampler
  from ultranest.stepsampler import select_random_livepoint, IslandPopulationRandomLivepointSelector
  from numpy.testing import assert_allclose
label_desc: Use image node_id 9 for calling a global function with example usage: test_stepsampler_variable_speed_SLOW(plot) without return types