Thanks @sgugger, @Narsil great to know.
@Narsil can I add a normalizer to a pretrained tokenizer and expect the same behaviour? Do pretrained tokenizers have their own normalizers that I might over-write by accident?
Would something like the below work as expected or would I be interfering with what the pretrained tokenizer does?
tokenizer = AutoTokenizer.from_pretrained('bert-base-uncased')
tokenizer.normalizer = normalizers.NFKC()
tokenizer('Am I working?')