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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 set_notebook_title(notebook, page_num, title_label):
 """Set the title of a GTK notebook to one of its tab's titles :param notebook: The GTK notebook :param page_num: The page number of a specific tab :param title_label: The GTK label holding the notebook's title :return: The new title of the notebook """

    text = get_notebook_tab_title(notebook, page_num)
    set_label_markup(title_label, text, constants.INTERFACE_FONT, constants.FONT_SIZE_BIG, constants.LETTER_SPACING_1PT)
    return text