pytorch-transformers

https://github.com/huggingface/transformers/blob/546dc24e0883e5e9f5eb06ec8060e3e6ccc5f6d7/src/transformers/models/gpt2/modeling_gpt2.py#L698

Assertions can't be relied upon for control flow because they can be disabled, as per the following:

$ python --help
usage: python [option] ... [-c cmd | -m mod | file | -] [arg] ...
...
-O     : remove assert and __debug__-dependent statem

Feature Request

Description of Problem:

We've taken a fairly risky/bad approach by just resorting to setting function params to arbitrary defaults when they aren't passed in. While this works sometimes, I think we've overused this approach and should really trim parts of it down.

Potential Solutions:

Eliminate optional parameters in any non-public function, and actually throw ex