Equal

declare function equals<B>(that: B): <A>(self: A) => boolean;
declare function equals<A, B>(self: A, that: B): boolean;

declare function isEqual(u: unknown): u is Equal;

declare const equivalence: <A>() => Equivalence<A>;

interface Equal extends Hash {
  [symbol](that: Equal): boolean;
}

declare const symbol: unique symbol;