Sorry for the delay in reviewing. I have been traveling and did not see this PR.

It seems given that EXTRACT has a special syntax, and the current implementation introduces some additional checks at multiple places to deal with them. I think this is not ideal in terms of OOP. Would it be possible to have a special subclass and implement the variability in methods that are overwritten?

Sorry for the delay in reviewing. I have been traveling and did not see this PR.

It seems given that EXTRACT has a special syntax, and the current implementation introduces some additional checks at multiple places to deal with them. I think this is not ideal in terms of OOP. Would it be possible to have a special subclass and implement the variability in methods that are overwritten?

Sounds good, just made some changes about that

I just noticed that there is a test failure (" time zone "g+zvi" not recognized"). Could you run the changed implementation for longer to check whether there are other errors that need to be added as expected errors?