Macro impl_unsigned_signed 

macro_rules! impl_unsigned_signed {
    ($([$($tt:tt)*])*) => { ... };
    ($unsigned:ident $signed:ident $upperty:ident) => { ... };
    (u128 i128) => { ... };
    (@inner $unsigned:ident $signed:ident $mod_mul:item) => { ... };
}