code: def preprocess_topics(source_groupid, source_topics, dest_groupid, topics_dest_group):
      
      # Is the new consumer already subscribed to any of these topics?
      common_topics = [topic for topic in topics_dest_group if topic in source_topics]
      if common_topics:
          print(
              "Error: Consumer Group ID: {groupid} is already "
              "subscribed to following topics: {topic}.\nPlease delete this "
              "topics from new group before re-running the "
              "command.".format(
                  groupid=dest_groupid,
                  topic=', '.join(common_topics),
              ),
              file=sys.stderr,
          )
          sys.exit(1)
      # Let's confirm what the user intends to do.
      if topics_dest_group:
          in_str = (
              "New Consumer Group: {dest_groupid} already "
              "exists.\nTopics subscribed to by the consumer groups are listed "
              "below:\n{source_groupid}: {source_group_topics}\n"
              "{dest_groupid}: {dest_group_topics}\nDo you intend to copy into"
              "existing consumer destination-group? (y/n)".format(
                  source_groupid=source_groupid,
                  source_group_topics=source_topics,
                  dest_groupid=dest_groupid,
                  dest_group_topics=topics_dest_group,
              )
          )
          prompt_user_input(in_str)
docs: Pre-process the topics in source and destination group for duplicates.