Macro combine_rdf_parser_impl

macro_rules! combine_rdf_parser_impl {
    (
        $(#[$derive:meta])*
        $struct_vis: vis struct $type_name: ident;
        $(#[$attr:meta])*
        $fn_vis: vis fn $name: ident [$($type_params: tt)*]( $($arg: ident :  $arg_type: ty),*)
            ($input_type: ty) -> $output_type: ty
            where [$($where_clause: tt)*]
        $parser: block
    ) => { ... };
}

Auxiliary macro that is invoked from rdf_parser which supports different templates