code: def merge_networks(output_file="merged_network.txt", *files):
      
  
      contacts = dict()
      for network_file in files:
          with open(network_file) as network_file_handle:
              for line in network_file_handle:
                  id_a, id_b, n_contacts = line.split("\t")
                  pair = sorted((id_a, id_b))
                  try:
                      contacts[pair] += n_contacts
                  except KeyError:
                      contacts[pair] = n_contacts
  
      sorted_contacts = sorted(contacts)
      with open(output_file, "w") as output_handle:
          for index_pair in sorted_contacts:
              id_a, id_b = index_pair
              n_contacts = contacts[index_pair]
              output_handle.write("{}\t{}\t{}\n".format(id_a, id_b, n_contacts))
docs: Merge networks into a larger network.
  
      A naive implementation for merging two networks in edgelist format.
  
      Parameters
      ---------
      output_file : file, str, or pathlib.Path, optional
          The output file to write the merged network into. Default is
          merged_network.txt
      `*files` : file, str or pathlib.Path
          The network files to merge.
  
      Note
      ----
      The partitioning step doesn't mind redundant
      edges and handles them pretty well, so if you are not
      using the merged edgelist for anything else you can just
      concatenate the edgelists without using this function.