Thanks a lot for the reply @Maimonator !! I had missed putting the max_length arg 
I am getting this new error:-
ValueError: expected sequence of length 2000 at dim 1 (got 1981)
Simply put - my tokenization just function doesn’t work  Can you see the code I posted on the StackOverflow link for my tok function and how I use the dataset.map to apply it to my dataset?
I personally can’t figure out why it doesn’t work