// Param-string JIT HostCall PoC (charCodeAt)
box Utils {
    codeAt(s, i) {
        return s.charCodeAt(i)
    }
}

u = new Utils()
print(u.codeAt("ABC", 0))
print(u.codeAt("ABC", 1))
print(u.codeAt("ABC", 2))
print(u.codeAt("ABC", 3)) // -1 (out of range)