Macro impl_bounded_tuple 

macro_rules! impl_bounded_tuple {
    (@impl $($T:ident)*) => { ... };
    (@inner $($T:ident)*,) => { ... };
    (@inner $($T:ident)*, $U:ident $($Rest:ident)*) => { ... };
    ($T:ident $($Rest:ident)*) => { ... };
}