def METHOD_NAME(self, letter):
    list_copy = list(map(lambda item: item.get_string(), self.str_list_letters))
    self.str_list_letters.splice(0, self.str_list_letters.get_n_items())
    for item in self.__alphabet:
        if item in list_copy or item == letter:
            self.str_list_letters.append(item)
    self.combo_letter.set_selected(0)