
Fix the following UCLID5 code using the compiler feedback provided below.

```

module main {
    // You must define a specific value for a const declaration in UCLID5.
    const n : int = 10;

    type stack_t = [int] int;

    // State variables
    var s : stack_t; // modeling the stack
    var top_index : int; // index indicating the top of the stack

    init {
        // Initial configuration of the stack
        top_index = -1; // indicates that the stack is empty
    }

    // Operations on the stack
    define is_empty(top_index : int) : boolean {
        return top_index == -1;
    }

    define is_full(top_index : int) : boolean {
        return top_index == n-1;
    }

    define top(s : stack_t, top_index : int) : int {
        if (is_empty(top_index)) {
            return 0; // return 0 if stack is empty (abstracting values)
        } else {
            return s[top_index];
        }
    }

    next {
        if (*) {
            // Push operation
            if (!is_full(top_index)) {
                var new_elem : int;
                new_elem = choose v : int :: v >= 0;
                top_index = top_index + 1;
                s[top_index] = new_elem;
            }
        } else if (*) {
            // Pop operation
            if (!is_empty(top_index)) {
                top_index = top_index - 1;
            }
        } else {
            // No-operation (the stack remains unchanged)
        }
    }

    invariant "top_index_within_bounds" {
        top_index >= -1 && top_index < n
    }

    control {
        liveness "can_push_if_not_full" {
            !is_full(top_index) => eventually (!is_full(top_index) && top_index' > top_index)
        }
    }
}
```

Compiler feedback:

```
Syntax error on line 18: .
    define is_empty(top_index : int) : boolean {

```
Reply with your UCLID5 code inside one unique code block.

I can definitely do that! Here is the UCLID5 code:
```
