code: def test_sum(graphtype):
      g = graphtype(2, 1)
      g.add_node(2)
  
      print(
          "Expected to go all the way to 20 without increasing the memory requirements..."
      )
      for i in range(20):
          print(i, end=" ")
          g.sum_edge(0, 1, 1, 2)
  
      v1 = g.get_edge(0, 1)
      v2 = g.get_edge(1, 0)
      print(
          "\nFinal edge weight should be 20 resp. 40. Found {} resp. {}".format(
              v1, v2
          )
      )
  
file_path: medpy/lib/maxflow/src/sum_edge_test.py
imports: from maxflow import GraphDouble, GraphFloat, GraphInt
  import random
label_desc: Use image node_id 3 for calling a global function with example usage: test_sum(graphtype) without return types