docs: def build_defaults(self, defaults_node):
          """parse `defaults` sections, and return a config.Defaults
  
          Args:
              defaults_node (TreeNode): Description
  
          Returns:
              config.Defaults: an object
          """
          proxy_name = defaults_node.defaults_header.proxy_name.text
          config_block_lines = self.__build_config_block(
              defaults_node.config_block)
          return config.Defaults(
              name=proxy_name,
              config_block=config_block_lines)