code: def test_desc_merge():
      """Test descending merge"""
      hroi = make_hroi()
      parents = np.arange(hroi.k)
      parents[1] = 0
      hroi.parents = parents
      s1 = hroi.get_size(0) + hroi.get_size(1)
      hroi.merge_descending()
      assert hroi.get_size()[0] == s1
  
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 10 for calling a global function with example usage: test_desc_merge() without return types