code: def sequences_add_end_id(sequences, end_id=888):
      
      sequences_out = [[] for _ in range(len(sequences))]  #[[]] * len(sequences)
      for i, _ in enumerate(sequences):
          sequences_out[i] = sequences[i] + [end_id]
      return sequences_out
docs: Add special end token(id) in the end of each sequence.
  
      Parameters
      -----------
      sequences : list of list of int
          All sequences where each row is a sequence.
      end_id : int
          The end ID.
  
      Returns
      ----------
      list of list of int
          The processed sequences.
  
      Examples
      ---------
      >>> sequences = [[1,2,3],[4,5,6,7]]
      >>> print(sequences_add_end_id(sequences, end_id=999))
      [[1, 2, 3, 999], [4, 5, 6, 999]]