def METHOD_NAME(self, event):
    index = self.listbox.index("active")
    if self.listbox.selection_includes(index):
        index = index + 1
    else:
        index = 0
    if index >= self.listbox.size():
        self.listbox.bell()
    else:
        self.select(index)
        self.on_select(index)
    return "break"