// Below, `Cipher` is not a "real" type. You never construct values of it.
#[fhe_program(scheme = "bfv")]
fn add_and_mul(a: Signed, b: Cipher<Signed>) -> (Cipher<Signed>, Cipher<Signed>) {
    (a + b, a * b)
}

let prog = add_and_mul.compile()?;
let runtime = add_and_mul.runtime()?;

let a = Signed::from(5);
// b instead has type `Ciphertext`
let b = runtime.encrypt(Signed::from(10), &public_key)?;

// runtime::run accepts a vector of inputs, so they all need to be casted to the `FheProgramInput` type.
let args: Vec<FheProgramInput> = vec![a.into(), b.into()];
let result = runtime
    .run(prog, args, &public_key)
    .unwrap();

let c: Signed = runtime.decrypt(&result[0], &private_key)?;
let d: Signed = runtime.decrypt(&result[1], &private_key)?;

// Now `Cipher<Signed>` is a real type - it's what you get when you encrypt a `Signed` value.
#[fhe_program(scheme = "bfv")]
fn add_and_mul(a: Signed, b: Cipher<Signed>) -> (Cipher<Signed>, Cipher<Signed>) {
    (a + b, a * b)
}

let runtime = add_and_mul.runtime()?;

let a = Signed::from(5);
// Here b has type `Cipher<Signed>`.
let b = runtime.encrypt(Signed::from(10), &public_key)?;

// Here the user passes in typed arguments and gets typed return values.
let (c_enc, d_enc) = add_and_mul.run(&runtime, &public_key, a, b)?;

let c: Signed = runtime.decrypt(&c_enc, &private_key)?;
let d: Signed = runtime.decrypt(&d_enc, &private_key)?;