Macro gcollections::forward_all_binop

macro_rules! forward_all_binop {
    (impl<$($bn:ident: $(+ $bs:ident)*),*> $imp:ident for $res:ty, $method:ident, $arg:ty) => { ... };
    (impl<$($bn:ident: $(+ $bs:ident)*),*> $imp:ident for $res:ty, $method:ident) => { ... };
}