<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def pad_sentences(sentences, padding_word="</s>"):
 """Pads all sentences to the same length. The length is defined by the longest sentence. Returns padded sentences. """

    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