new_contents: __author__ = 'Archana V Menon, Sujith V'
  
  import networkx as nx
  
  def min_edge_dominating_set(G):
  
      """
      Find minimum edge dominating set
  
      :param G: networkx graph
      :return: set of edges
      :raise ValueError: when graph is null
      """
  
      if not G:
          raise ValueError("Error : null graph")
  
      return nx.maximal_matching(G)
  
  
  if __name__ == "__main__":
  
      # get graph
      from read_graph import read_graph
      G = read_graph("data/roadNet-CA.txt")
  
      # find approximate dominating set
      ds = min_edge_dominating_set(G)
  
      print ds
subject: add approx dom set script