Issue with models not using position_ids

[kfertakis]

I think this issue relates to #217 and #218. Some models, for example facebook/opt-1.3b, don't accept position_ids as an argument and current implementation using it (used here, here and here) leads to the following error. Is there a way this argument is conditional to whether the model used supports it as input?

TypeError: OPTModel.forward() got an unexpected keyword argument 'position_ids'

Thank you,

[hijkzzz]

Interesting issue. Let me figure out how to fix it.