class_docstr: Test hungarian matcher.
docstr: Ensure that implicit use of slicer works.
docstr_tok: ["Ensure","that","implicit","use","of","slicer","works","."]
code: def test_slicer_implicit(self, matcher_fn):
      """Ensure that implicit use of slicer works."""
      n_cols = self.cost_n_cols // 2
      mask = np.concatenate(
          (
              np.ones((1, n_cols[0]), dtype=bool),
              np.zeros((1, self.num_preds - n_cols[0]), dtype=bool),
          ),
          axis=1,
      )
      cost = mask * self.cost_matrix + (1.0 - mask) * 5
  
      ind_slicer_impl = matcher_fn(cost, n_cols=n_cols)
      ind_slicer = matchers.slicer(cost, n_cols, matcher_fn)
  
      for i, (
          (impl_row, impl_col),
          (slicer_row, slicer_col),
      ) in enumerate(zip(ind_slicer_impl, ind_slicer)):
          impl_cost = cost[i, impl_row, impl_col].sum()
          slicer_cost = cost[i, slicer_row, slicer_col].sum()
          self.assertAlmostEqual(impl_cost, slicer_cost, places=3)
  
imports: from typing import Optional
  from absl.testing import absltest
  from absl.testing import parameterized
  import jax
  import jax.numpy
  import numpy
  from scenic.model_lib import matchers
  from scenic.model_lib.base_models import box_utils
  import scipy.optimize
label_desc: Use image node_id 9 for calling the MatchingTest obj's underlying member method code with example usage: obj.test_slicer_implicit(matcher_fn) without return types