********** source program **********
fn f Int: x -> Int {
return 0;

}
fn main () -> Int {
var Int: a = 0;
var Int: b = 1;
f(0 = a);
b = a;
return b;

}
********** type checking **********
--- step exp Int --->
--- step exp Int --->
--- step exp Int --->
--- step exp Int --->
--- step exp Int --->
--- step exp Int --->
--- step exp Int --->
--- step exp Int --->
15: type error in call
expected: Int
actual: Tuple(0 = Int)
EXIT CODE: 255