
pub trait Sealed {}

macro_rules! impl_sealed {
    ($($T: ident)*) => {$(
        impl Sealed for $T {}
    )*}
}

impl_sealed! {
    u8 u16 u32 u64 u128 usize
    i8 i16 i32 i64 i128 isize
    f32 f64
    bool char
}