code: def test_unreachable(self):
      n = 5
      assert n > 1
      G = nx.path_graph(n, create_using=nx.DiGraph())
      assert nx.immediate_dominators(G, n // 2) == {
          i: max(i - 1, n // 2) for i in range(n // 2, n)
      }
  
imports: import pytest
  import networkx
label_desc: Use image node_id 5 for calling the TestImmediateDominators obj's underlying member method code with example usage: obj.test_unreachable() without return types