Unions and literals

type City = "Nairobi" | "Mombasa" | "Kisumu";
const city: City = "Nairobi";
console.log(city);

type City = "Nairobi" | "Mombasa" | "Kisumu";
function coast(city: City): boolean {
  return city === "Mombasa";
}
console.log(coast("Mombasa"));
console.log(coast("Kisumu"));

type UnitsOrNone = number | null;
const missing: UnitsOrNone = null;
console.log(missing);

type Status = "busy" | "quiet";
const status: Status = "busy";
console.log(status);