Interface methods

interface methods {
    _type: bigint;
    between<Min extends bigint, Max extends bigint>(
        minimum: Min,
        maximum: Max,
    ): t_bigint.between<[min: Min, max: Max]>;
    max<Max extends bigint>(maximum: Max): t_bigint.max<Max>;
    min<Min extends bigint>(minimum: Min): t_bigint.min<Min>;
    (u: unknown): u is bigint;
}