trait IsSend  {
    fn is_send(&self);
}

impl<T: Send + 'static> IsSend for T {
    fn is_send(&self){
        println!("T = {:?}", std::any::TypeId::of::<T>())
    }
}

fn main() -> Result<(),Box<dyn std::error::Error>> {
     println!("TypeId for Rc<i32>: {:?}", std::any::TypeId::of::<std::rc::Rc<i32>>());
     println!("TypeId for i32: {:?}", std::any::TypeId::of::<i32>());

     let i = std::rc::Rc::new(43i32);
     i.is_send(); // (!!) no compiler error although Rc is not Send
     Ok(())
}