How to use the jsbi.exponentiate function in jsbi

JSBI.BigInt('34');
JSBI.BigInt('00034');

const JSBigInt = JSBI.BigInt;
JSBigInt(34);
const JSBigInt2 = JSBI['BigInt'];
JSBigInt2(56);
const JSBIadd = JSBI.add;
JSBIadd(7, 8);

JSBI.add(a, b);
JSBI.subtract(a, b);
JSBI.multiply(a, b);
JSBI.divide(a, b);
JSBI.remainder(a, b);
JSBI.exponentiate(a, b);
const c = JSBI.unaryMinus(a);
const d = JSBI.bitwiseNot(a);
JSBI.leftShift(a, b);
JSBI.signedRightShift(a, b);
JSBI.bitwiseAnd(a, b);
JSBI.bitwiseOr(a, b);
JSBI.bitwiseXor(a, b);

JSBI.equal(a, b);
JSBI.notEqual(a, b);
JSBI.lessThan(a, b);
JSBI.lessThanOrEqual(a, b);
JSBI.greaterThan(a, b);
JSBI.greaterThanOrEqual(a, b);

JSBI.EQ(a, b);

private static calculateSizeThreshold(numberOfBytes: number): JSBI {
        let exponent: JSBI = JSBI.multiply(JSBI.BigInt(numberOfBytes), this.BITS_PER_BYTE);
        let threshold = JSBI.exponentiate(JsbiSupport.TWO, exponent);
        return JSBI.subtract(threshold, JsbiSupport.ONE);
    }
}