code: def process_tree_files(tree):
      
      # Fill in values necessary for next steps
      config.LOGGER.info("Processing content...")
      files_to_diff = tree.process_tree(tree.channel)
      config.SUSHI_BAR_CLIENT.report_statistics(files_to_diff, topic_count=tree.channel.get_topic_count())
      tree.check_for_files_failed()
      return files_to_diff, config.FAILED_FILES
docs: process_tree_files: Download files from nodes
          Args:
              tree (ChannelManager): manager to handle communication to Kolibri Studio
          Returns: None