use hash::Hash;
pub trait Key: Sized + Copy + Default + PartialEq + Eq + Hash {}
impl<T> Key for T
where
T: Sized + Copy + Default + PartialEq + Eq + Hash,
{
}
pub trait Value: Sized + Copy + Default {}
impl<T> Value for T
where
T: Sized + Copy + Default,
{
}