text: Title: ABOUT SRC_TOKENS
  Body: In TransformerEncoderBase class, it's forward() function has a parameter 'src_tokens': tokens in the source language of shape `(batch, src_len)`.
  It's a tensor of indexes, suppoes that:
  [ [10, 52, 138, ....],
    [53, 108, 52, ....],
    ...............
    [28, 82, 106, ....] ]
  
  How can i get the word in the raw input text that corresponds to each index?
  Suppose that:
  [ ['I', 'want', 'to', ...],
    ['Today', 'I', 'have',...],
    ...........................
    ['this', 'movie', 'is', ...] ]
  
  Thank you very much!
  <img width="511" alt="image" src="https://github.com/facebookresearch/fairseq/assets/105722903/fd2db0d8-a565-4711-9af4-c6ac7ba0473a">
  