[logprob] to force llm to select from a list of options as output.

[liyin2015]

For models, especially open source ones with logprob available, we can potentially force model to select from a set of options such as select(["apple", "orange"). this is very helpful for using genai to do classification tasks.

This can be a parser_completion function in the model_client where user can customize.

Guidance: https://github.com/guidance-ai/guidance/

[dasdebanna]

Hello @liyin2015 is this issue open or resolved. If it's not resolved I'm interested in working on this.