operator `=`[T](a: var T, b: T) {
    #pragma[magic: "GenericAssign"]
}


operator `+`(a, b: int): int {
    #pragma[magic: "AddInt64", pure]
}


operator `+=`(a: var int, b: int) {
    a = a + b;
}


fn identity(x: var int): int {
    x += 1;
    return x;
}


var x = 5;
identity(x);
# identity(38);  # If you uncomment this, the compiler errors out!