To ASCII

# Text into ASCII fails `not_ascii` unless every character is ASCII (owner, 2026-09-30: "`otherwise`
# exists"). Into utf16 or utf32 it never fails, and from ASCII text there is nothing to fail.
MAIN {
    let 'plain': str.utf8 = "hello";
    let 'accented': str.utf8 = "héllo";
    let 'a' := to.str.ascii['plain'] otherwise "?";
    let 'b' := to.str.ascii['accented'] otherwise "not ascii";
    std::print.stored['a', newln, 'b', newln];
    let 's': str.ascii = "abc";
    let 'c' := to.str.ascii['s'];
    let 'w' := to.str.utf16['accented'];
    std::print.stored['c', " ", 'w', newln];
}