@Override
    public boolean onExecute() {
        getArg().execute();
        getResult().set(getArg().getResult());
        getResult().negate();
        return true;
    }
Constructs an instance of this class with given argument.

@param arg The argument for this function.
searchlib/src/main/java/com/yahoo/searchlib/expression/NegateFunctionNode.java