Macro ast_fragments

macro_rules! ast_fragments {
    (
        $($Kind:ident($AstTy:ty) {
            $kind_name:expr;
            $(one
                fn $mut_visit_ast:ident;
                fn $visit_ast:ident;
                fn $ast_to_string:path;
            )?
            $(many
                fn $flat_map_ast_elt:ident;
                fn $visit_ast_elt:ident($($args:tt)*);
                fn $ast_to_string_elt:path;
            )?
            fn $make_ast:ident;
        })*
    ) => { ... };
}