langchain[patch]: Improve HyDe with custom prompts and ability to supply the run_manager (#14016)
- **Description:** The class allows to only select between a few
predefined prompts from the paper. That is not ideal, since other use
cases might need a custom prompt. The changes made allow for this. To be
able to monitor those, I also added functionality to supply a custom
run_manager.
- **Issue:** no issue, but a new feature,
- **Dependencies:** none,
- **Tag maintainer:** @hwchase17,
- **Twitter handle:** @yvesloy
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Co-authored-by: Bagatur <baskaryan@gmail.com>