Héctor Sab

### Subject of the issue When using the `Optional` type hint, I can no longer convert from a json string into the data class. ### Steps to reproduce The following...

### Subject of the issue When using `from __future__ import annotations` ([PEP 563 -- Postponed Evaluation of Annotations](https://www.python.org/dev/peps/pep-0563)) I get Errors of type `TypeError: isinstance() arg 2 must be a...