code: def test_visibility_graph__single_value_ts__single_node_graph():
      node_graph = nx.visibility_graph([10])  # So Lonely
      assert node_graph.number_of_nodes() == 1
      assert node_graph.number_of_edges() == 0
  
file_path: networkx/networkx/generators/tests/test_time_series.py
imports: import itertools
  import networkx
label_desc: Use image node_id 2 for calling a global function with example usage: test_visibility_graph__single_value_ts__single_node_graph() without return types