fn start() {
    // Allocate 128 bytes of memory and store the pointer to that block in `str`
    def size = 128;
    def str = alloc(size);
    free(str, size);
}

// free_byte only frees a single cell, so free must be implemented manually
fn free(ptr, size) {
    while size {
        size = sub(size, 1);
        // free_byte is built in
        free_byte(add(ptr, size));
    }

    // Store 0 in the return register
    return 0;
}