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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 popd():
 """Go back to where you once were. :return: saved directory stack """

    try:
        directory = _saved_paths.pop(0)
    except IndexError:
        return [os.getcwd()]
    os.chdir(directory)
    return [directory] + _saved_paths