Actually, it may not be very important.
I am confused about the prefix too and ask on the Github. And one of the code author replied. (there are more questions, you may benefit from it too as a beginner)

  
      github.com/huggingface/transformers
  
  
    
  
	  
  

  
    
      Fine tune T5 for paraphrase generation 111
    

    
      
        opened 
        
          
        
        Jul 24, 2020
      
      


      
        
          
          mengyahuUSTC-PU
        
      
    
  



  ❓ Questions & Help
Dear all,
I am new to NLP and has a lot of questions. Sorry to ask this long list...