Macro impl_contains_token_for_tuples

macro_rules! impl_contains_token_for_tuples {
    ($haystack1:ident, $($haystack:ident),+) => { ... };
    (__impl $($haystack:ident),+; $haystack1:ident $(,$haystack2:ident)*) => { ... };
    (__impl $($haystack:ident),+;) => { ... };
}