declare const label: unique symbol;

export type LabelContainer<Token> = {
	readonly [label]?: Token;
  //              ^ This the only difference between Label and Opaque
};

export type Label<Type, Token = unknown> = Type & LabelContainer<Token>;

type NormalString = string
type PatternString = Label<string, "PatternString">

type Options = {
  prefix: NormalString,
  pattern: PatternString,
  opaquePattern: OpaquePatternString
}

let options: Options = {
  prefix: "foo/",
  // ^? (property) prefix: string
  pattern: "{bar,baz}"
  // ^? (property) pattern: PatternString
}

// No `as PatternString` or `patternString("...")`
let pattern: PatternString = "{bar,baz}"