parse `backend` sections

        Args:
            backend_node (TreeNode): Description

        Returns:
            config.Backend: an object

def build_backend(self, backend_node):
        """parse `backend` sections

        Args:
            backend_node (TreeNode): Description

        Returns:
            config.Backend: an object
        """
        proxy_name = backend_node.backend_header.proxy_name.text
        config_block_lines = self.__build_config_block(
            backend_node.config_block)
        return config.Backend(name=proxy_name, config_block=config_block_lines)