code: def test_desc_merge_2():
      """Test descending merge"""
      hroi = make_hroi()
      parents = np.arange(-1, hroi.k - 1)
      parents[0] = 0
      hroi.parents = parents
      hroi.set_roi_feature("labels", np.arange(hroi.k))
      labels2 = [hroi.label[hroi.label == k] for k in range(hroi.k)]
      hroi.set_feature("labels2", labels2)
      hroi.merge_descending()
      assert hroi.k == 1
      assert len(hroi.get_feature("labels2")) == hroi.k
      assert hroi.get_roi_feature("labels").size == hroi.k
  
imports: import numpy
  from numpy.testing import assert_array_equal
  from ..discrete_domain import domain_from_binary_array
  from ..hroi import HROI_as_discrete_domain_blobs, make_hroi_from_subdomain
  from ..mroi import subdomain_from_array
label_desc: Use image node_id 11 for calling a global function with example usage: test_desc_merge_2() without return types