code: def propagate_defaults(config_doc):
      
      for group_name, group_doc in config_doc.items():
          if isinstance(group_doc, dict):
              defaults = group_doc.get('defaults', {})
  
              for item_name, item_doc in group_doc.items():
                  if item_name == 'defaults':
                      continue
                  if isinstance(item_doc, dict):
  
                      group_doc[item_name] = \
                          dict_merge_pair(copy.deepcopy(defaults), item_doc)
  
      return config_doc
docs: Propagate default values to sections of the doc.