@Override
    public double doubleValue() {
        return (double) numerator / (double) divisor;
    }
A private constructor for methods such as negate() that create instances of this class using the content of the current instance.

@param numerator    a valid numerator
@param divisor      a valid denominator
@param unsignedType indicates how numerator and divisor values are to be interpreted.
src/main/java/org/apache/commons/imaging/common/RationalNumber.java