Refactored itf.__dict__ to vars(itf)

[newwingbird]

Proposal

Related to #472

I chose to use vars function because dunder/magic methods serve as the implementation, while invoking functions/methods acts as the API.

note

https://stackoverflow.com/questions/21297203/use-dict-or-vars

[junkmd]

These lines used a complex way of catching exceptions to maintain compatibility between Python 2.x and Python 3.x.

Now, the same thing can be written without catching exceptions. Thanks to your efforts, the code has been modernized.