Macro permutation_trait

macro_rules! permutation_trait {
    (
    $name1:ident $ty1:ident $item1:ident
    $name2:ident $ty2:ident $item2:ident
    $($name3:ident $ty3:ident $item3:ident)*
  ) => { ... };
    (
    __impl $($name:ident $ty:ident $item:ident),+;
    $name1:ident $ty1:ident $item1:ident $($name2:ident $ty2:ident $item2:ident)*
  ) => { ... };
    (__impl $($name:ident $ty:ident $item:ident),+;) => { ... };
}