Python-implementable kvstores

[normanrz]

In a recent meeting, @jbms, I and others discussed that it would be useful to expose a Python interface to implement custom kvstores. This would allow library users to implement their own storage backends such as S3, Azure, Webdav more easily. That could also open the door to the rich fsspec ecosystem.

[myron0330]

Is there any practice could be referred to ?