struct Calculator<C>
    where C: Fn(u32, u32) -> u32
{
    context: (u32, u32),
    calculate: C,
}

impl<C> Calculator<C>
    where C: Fn(u32, u32) -> u32
{
    fn new(lhs: u32, rhs: u32, calculate: C) -> Self
    {
        Self { context: (lhs, rhs), calculate }
    }

    fn execute(&self) -> u32
    {
        let (lhs, rhs) = self.context;
        (self.calculate)(lhs, rhs)
    }
}

fn main()
{
    let c1 = Calculator::new(12, 33, |l, r| l + r);
    let c2 = Calculator::new(3, 5, |l, r| l*r);

    let x = 12;
    let c3 = Calculator::new(66, 4, |l, r| l + x + r);

    dbg!(c1.execute());
    dbg!(c2.execute());
    dbg!(c3.execute());
}