code: def test_notbranching1():
      # Acyclic violation.
      G = nx.MultiDiGraph()
      G.add_nodes_from(range(10))
      G.add_edges_from([(0, 1), (1, 0)])
      assert not nx.is_branching(G)
      assert not nx.is_arborescence(G)
  
imports: import pytest
  import networkx
label_desc: Use image node_id 7 for calling a global function with example usage: test_notbranching1() without return types