// @dynamic
// Astral-plane and special-cased strings cross the boundary intact (UTF-8
// on the static side, engine UTF-16 inside): supplementary-plane case
// pairs (Deseret), 1:many mappings (ß → SS), context-sensitive Greek final
// sigma, and split on an astral separator.
const deseret = "\u{10437}\u{10437}";
const upper = deseret.toUpperCase();
console.log(upper, upper.length, upper.charCodeAt(0));
const mixed = "α😀β😀γ";
const bits = mixed.split("😀");
console.log(bits.length, bits.join("+"), bits[1].length);
console.log("straße".toUpperCase());
console.log("ΣΊΣΥΦΟΣ".toLowerCase());
console.log("😀!".padStart(6, "🌍").length, "a😀b😀".replaceAll("😀", "🌍"));