code: def pad_sentences(sentences, padding_word="</s>"):
      
      sequence_length = max(len(x) for x in sentences)
      padded_sentences = []
      for i, sentence in enumerate(sentences):
          num_padding = sequence_length - len(sentence)
          new_sentence = sentence + [padding_word] * num_padding
          padded_sentences.append(new_sentence)
      return padded_sentences
docs: Pads all sentences to the same length. The length is defined by the longest sentence.
      Returns padded sentences.