This PR targets the `API Reference` documentation.
- Several classes and functions missed `docstrings`. These docstrings
were created.
- In several places this
```
except ImportError:
raise ValueError(
```
was replaced to
```
except ImportError:
raise ImportError(
```
Any import that touches langchain.retrievers currently requires Lark.
Here's one attempt to fix. Not very pretty, very open to other ideas.
Alternatives I thought of are 1) make Lark requirement, 2) put
everything in parser.py in the try/except. Neither sounds much better
Related to #4316, #4275
Alternate implementation of #3452 that relies on a generic query
constructor chain and language and then has vector store-specific
translation layer. Still refactoring and updating examples but general
structure is there and seems to work s well as #3452 on exampels
---------
Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>
Leonid Ganeline