raisedTo(exponent) {
        if (exponent === 0.5 && this.imag === 0 && this.real >= 0) {
            return new Complex(Math.sqrt(this.real), 0);
        }
        if (Complex.ZERO.isEqualTo(exponent)) {
            return Complex.ONE;
        }
        if (this.isEqualTo(Complex.ZERO)) {
            return Complex.ZERO;
        }
        return this.ln().times(Complex.from(exponent)).exp();
    }
Returns the result of raising the receiving complex value to the given complex exponent.
@param {!number|!Complex} exponent
@returns {!Complex}