code: def test_k_truss(self):
      # k=-1
      k_truss_subgraph = nx.k_truss(self.G, -1)
      assert sorted(k_truss_subgraph.nodes()) == list(range(1, 21))
      # k=0
      k_truss_subgraph = nx.k_truss(self.G, 0)
      assert sorted(k_truss_subgraph.nodes()) == list(range(1, 21))
      # k=1
      k_truss_subgraph = nx.k_truss(self.G, 1)
      assert sorted(k_truss_subgraph.nodes()) == list(range(1, 21))
      # k=2
      k_truss_subgraph = nx.k_truss(self.G, 2)
      assert sorted(k_truss_subgraph.nodes()) == list(range(1, 21))
      # k=3
      k_truss_subgraph = nx.k_truss(self.G, 3)
      assert sorted(k_truss_subgraph.nodes()) == list(range(1, 13))
  
      k_truss_subgraph = nx.k_truss(self.G, 4)
      assert sorted(k_truss_subgraph.nodes()) == list(range(1, 9))
  
      k_truss_subgraph = nx.k_truss(self.G, 5)
      assert sorted(k_truss_subgraph.nodes()) == []
  
imports: import pytest
  import networkx
  from networkx.utils import nodes_equal
label_desc: Use image node_id 19 for calling the TestCore obj's underlying member method code with example usage: obj.test_k_truss() without return types