@Override
public double numberFunction(TraversingInformer contextNode, TraverserDynamicContext dynEnv) {
return -expr.numberFunction(contextNode, dynEnv);
}
@Override
public <N> double numberFunction(
Model<N> model, final N contextNode, final NodeDynamicContext<N> dynEnv) {
return -expr.numberFunction(model, contextNode, dynEnv);
}