[Feature Request] Is it possiable to specify assertion on the expression to generate?

[hgzhehe]

To add assertions like
1、all the Xi must show up in the result.
2、or some Xm.. must/mustn't add/sub/etc with Xn..
3、 or some sub expression should/should not show up in the result

basicly to add some type to the result expression
It may be helpful sometimes to add human intelligence in advance

Please forgive my asking for possiable feature without learning about the algorithm and implementation.