code: def test_main_crust(self):
      main_crust_subgraph = nx.k_crust(self.H)
      assert sorted(main_crust_subgraph.nodes()) == [0, 1, 3]
  
imports: import pytest
  import networkx
  from networkx.utils import nodes_equal
label_desc: Use image node_id 11 for calling the TestCore obj's underlying member method code with example usage: obj.test_main_crust() without return types