* add document_store to retrieve()]
* mypy & pylint
* pass docstore to embedding encoders
* schemas
* mypy and pylint
* fix tfidfretriever
* pylint
* mypy
* pylint
* fix tfidf
* mypy
* pylint
* schemas
* another fix for tfidf
* fix question generation tests
* remove docstore from embedding encoder signature
* pylint
* revert accidental test changes
* Apply suggestions from code review
* check for docstore similarity function only if the docstore is present
* check for docstore similarity function only if the docstore is present