code: def cs_shc():
      graph = nx.Graph()
      graph.add_nodes_from([1, 2, 3, 4, 5])
      graph.add_edges_from(
          [(1, 2), (1, 5), (2, 3), (2, 4), (2, 5), (3, 4), (4, 5)]
      )
      return graph
  
imports: import itertools
  import pytest
  import networkx
label_desc: Use image node_id 18 for calling a global function with example usage: cs_shc() and returns: graph