human
Complete the below
def buffer():

    ''''A model to complete on open tabs across all windows.
    Used for switching the buffer command.'
    '''
assistant
#Here is the Python program you requested.
    def delete_buffer(data):
        'Close    the    selected    tab.'
        (win_id, tab_index) = data[0].split('/')
        tabbed_browser = objreg.get('tabbed-browser', scope='window', window=int(win_id))
        tabbed_browser.on_tab_close_requested((int(tab_index) - 1))
    model = completionmodel.CompletionModel(column_widths=(6, 40, 54))
    for win_id in objreg.window_registry:
        tabbed_browser = objreg.get('tabbed-browser', scope='window', window=win_id)
        if tabbed_browser.shutting_down:
            continue
        tabs = []
        for idx in range(tabbed_browser.count()):
            tab = tabbed_browser.widget(idx)
            tabs.append(('{}/{}'.format(win_id, (idx + 1)), tab.url().toDisplayString(), tabbed_browser.page_title(idx)))
        cat = listcategory.ListCategory('{}'.format(win_id), tabs, delete_func=delete_buffer)
        model.add_category(cat)
    return model