TemplateProcessing for encoder-decoder

I’ve seen the docs on how to define the encoding format with TemplateProcessing. For example for BERT it would be :

from tokenizers.processors import TemplateProcessing

tokenizer.post_processor = TemplateProcessing(
    single="[CLS] $A [SEP]",
    pair="[CLS] $A [SEP] $B:1 [SEP]:1",
    special_tokens=[("[CLS]", 1), ("[SEP]", 0)],

But what about encoder-decoder ? What I want to achieve is :

  • The encoder get a sentence with CLS and SEP : <cls> sen1 <sep>
  • The decoder get a sentence with BOS and EOS : <s> sen2 </s>

I call my tokenizer like : x = tokenizer([sen1], text_target=[sen2])

So my question is : how can I define TemplateProcessing to achieve this kind of format ?