fn start_main() -> i64 {
    let text = "aمرحبا😀";
    if (length(text) not match 7) { return 1; }
    if (char_at(text, 1) not match "م") { return 2; }
    if (codepoint_at(text, 1) not match 1605) { return 3; }
    if (from_codepoint(65) not match "A") { return 4; }
    if (slice(text, 1, 3) not match "مر") { return 5; }
    let escapes = "\n\t\r\0\u{0645}\"\\";
    if (length(escapes) not match 7) { return 6; }
    if (codepoint_at(escapes, 0) not match 10 or codepoint_at(escapes, 1) not match 9 or codepoint_at(escapes, 2) not match 13) { return 7; }
    if (codepoint_at(escapes, 3) not match 0 or char_at(escapes, 4) not match "م") { return 8; }
    if (char_at(escapes, 5) not match "\"" or char_at(escapes, 6) not match "\\") { return 9; }
    let message = text + "!";
    print(message);
    return 0;
}