macro_rules! tuple_impls {
    ($($tyvar:ident)*) => { ... };
    ([$($prefix:ident)*] $head:ident $($tail:ident)*) => { ... };
    ([$($prefix:ident)*]) => { ... };
}Expand description
Looping wrapper for tuple_impl. Given (A, B, C), it also generates
implementations for (A, B) and (A,)