This is a great addition, thank you!

We might want to reconsider the use of the cached_property decorator for __requests_session (and for __boto_session), which has a pretty serious problem for concurrent processing described here: python/cpython#87634
All instances of the class will share the same lock, blocking each other any time the cached property is accessed. This will definitely hurt performance if a user creates a threadpool to run many queries together.

It could be avoided by rearranging the current code, but keeping the same logic and sequence of operations:

class Client:

    def __init__(
        self,
        ...
        requests_session=None,
    ):
        ...
        self._requests_session = requests_session

    @property
    def __requests_session(self):
        """Requests session"""
        if self._requests_session is None:
            self._requests_session = Session()
        return self._requests_session