code: def test_spanner_trivial():
      """Test a trivial spanner with stretch 1."""
      G = nx.complete_graph(20)
      spanner = nx.spanner(G, 1, seed=_seed)
  
      for u, v in G.edges:
          assert spanner.has_edge(u, v)
  
file_path: networkx/networkx/algorithms/tests/test_sparsifiers.py
imports: import pytest
  import networkx
  from networkx.utils import py_random_state
label_desc: Use image node_id 3 for calling a global function with example usage: test_spanner_trivial() without return types