ZygoseitherisLeftOn this pageisLeft() isLeft<E>(ma): ma is Left<E> Type guard that checks if an Either is a Left. Type Parametersโ E: Eโ The error type. Parametersโ ma: Either<E, unknown>โ The Either to check. Returns: ma is Left<E>โ True if the Either is a Left. Sinceโ 2.0.0