parse `defaults` sections, and return a config.Defaults

        Args:
            defaults_node (TreeNode): Description

        Returns:
            config.Defaults: an object

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)