Macro impl_parser_for_tuples

macro_rules! impl_parser_for_tuples {
    ($index1:tt $parser1:ident $output1:ident, $($index:tt $parser:ident $output:ident),+) => { ... };
    (__impl $($index:tt $parser:ident $output:ident),+; $index1:tt $parser1:ident $output1:ident $(,$index2:tt $parser2:ident $output2:ident)*) => { ... };
    (__impl $($index:tt $parser:ident $output:ident),+;) => { ... };
}