@Override
    public MathPowFunction copy() {
        return new MathPowFunction(getLabel(),
                                   getLevelOrNull(),
                                   getArg(0).copy(),
                                   getArg(1).copy());
    }
Constructs a new instance of this class.

@param x The expression to evaluate for base, double value will be requested.
@param y The expression to evaluate for the exponent, double value will be requested.
container-search/src/main/java/com/yahoo/search/grouping/request/MathPowFunction.java