code: def update_network(cx_str, network_id, ndex_cred=None):
      
      server = 'http://public.ndexbio.org'
      username, password = get_default_ndex_cred(ndex_cred)
      nd = ndex2.client.Ndex2(server, username, password)
  
      try:
          logger.info('Getting network summary...')
          summary = nd.get_network_summary(network_id)
      except Exception as e:
          logger.error('Could not get NDEx network summary.')
          logger.error(e)
          return
  
      # Update network content
      try:
          logger.info('Updating network...')
          cx_stream = io.BytesIO(cx_str.encode('utf-8'))
          nd.update_cx_network(cx_stream, network_id)
      except Exception as e:
          logger.error('Could not update NDEx network.')
          logger.error(e)
          return
  
      # Update network profile
      ver_str = summary.get('version')
      new_ver = _increment_ndex_ver(ver_str)
      profile = {'name': summary.get('name'),
                 'description': summary.get('description'),
                 'version': new_ver,
                 }
      logger.info('Updating NDEx network (%s) profile to %s',
                  network_id, profile)
      profile_retries = 5
      for _ in range(profile_retries):
          try:
              time.sleep(5)
              nd.update_network_profile(network_id, profile)
              break
          except Exception as e:
              logger.error('Could not update NDEx network profile.')
              logger.error(e)
  
      set_style(network_id, ndex_cred)
docs: Update an existing CX network on NDEx with new CX content.
  
      Parameters
      ----------
      cx_str : str
          String containing the CX content.
      network_id : str
          UUID of the network on NDEx.
      ndex_cred : dict
          A dictionary with the following entries:
          'user': NDEx user name
          'password': NDEx password