Custom operation with pybitshares

Hi @xeroc ,
So, just wanted to use the blockchain as DB and wanted to store custom user data like email, bio...
After some finding I found custom operation plugin but don't have any direction, How to use it?
I looked into the JS library but that also not support the custom operations.

Does this library supports the custom operations?

Start by locating the pybitshares operation-building and transaction entry points, then compare them with the custom operation plugin and the JavaScript library mentioned in the issue. Determine whether custom operations are supported and what API or documentation is missing; done means the support question has a clear, tested answer or an agreed implementation scope.

索引モデルが issue の本文から書いたものです。