@Override
    public ConstantNode clone() {
        ConstantNode obj = (ConstantNode)super.clone();
        if (value != null) {
            obj.value = (ResultNode)value.clone();
        }
        return obj;
    }
This abstract expression node represents a function to execute.

@author baldersheim
@author Simon Thoresen Hult
searchlib/src/main/java/com/yahoo/searchlib/expression/ConstantNode.java