code: def replace_oovs(
      source_in, target_in, vocabulary, source_out, target_out
  ):
      """Replaces out-of-vocabulary words in source and target text with <unk-N>,
      where N in is the position of the word in the source sequence.
      """
  
      def format_unk(pos):
          return "<unk-{}>".format(pos)
  
      if target_in is None:
          target_in = []
  
      for seq_num, (source_seq, target_seq) in enumerate(
          zip_longest(source_in, target_in)
      ):
          source_seq_out = []
          target_seq_out = []
  
          word_to_pos = dict()
          for position, token in enumerate(source_seq.strip().split()):
              if token in vocabulary:
                  token_out = token
              else:
                  if token in word_to_pos:
                      oov_pos = word_to_pos[token]
                  else:
                      word_to_pos[token] = position
                      oov_pos = position
                  token_out = format_unk(oov_pos)
              source_seq_out.append(token_out)
          source_out.write(" ".join(source_seq_out) + "\n")
  
          if target_seq is not None:
              for token in target_seq.strip().split():
                  if token in word_to_pos:
                      token_out = format_unk(word_to_pos[token])
                  else:
                      token_out = token
                  target_seq_out.append(token_out)
          if target_out is not None:
              target_out.write(" ".join(target_seq_out) + "\n")
  
label_desc: Use image node_id 1 for calling a global function with example usage: replace_oovs(source_in, target_in, vocabulary, source_out, target_out) and returns: str