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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_contents(diff_part):
 """ Returns a tuple of old content and new content. """

    old_sha = get_old_sha(diff_part)
    old_filename = get_old_filename(diff_part)
    old_contents = get_old_contents(old_sha, old_filename)
    new_filename = get_new_filename(diff_part)
    new_contents = get_new_contents(new_filename)
    return old_contents, new_contents