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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 create_tab_header_label(tab_name, icons):
 """Create the tab header labels for notebook tabs. If USE_ICONS_AS_TAB_LABELS is set to True in the gui_config, icons are used as headers. Otherwise, the titles of the tabs are rotated by 90 degrees. :param tab_name: The label text of the tab, written in small letters and separated by underscores, e.g. states_tree :param icons: A dict mapping each tab_name to its corresponding icon :return: The GTK Eventbox holding the tab label """

    tooltip_event_box = Gtk.EventBox()
    tooltip_event_box.set_tooltip_text(tab_name)
    tab_label = Gtk.Label()
    if global_gui_config.get_config_value('USE_ICONS_AS_TAB_LABELS', True):
        tab_label.set_markup('<span font_desc="%s %s">&#x%s;</span>' %
                            (constants.ICON_FONT,
                            constants.FONT_SIZE_BIG,
                            icons[tab_name]))
    else:
        tab_label.set_text(get_widget_title(tab_name))
        tab_label.set_angle(90)
    tab_label.show()
    tooltip_event_box.add(tab_label)
    tooltip_event_box.set_visible_window(False)
    tooltip_event_box.show()
    return tooltip_event_box