<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _remove_overlapped_date_str(self, results: List[List[dict]]) -> List[Extraction]: """ some string may be matched by multiple date templates, deduplicate the results and return a single list """

        res = []
        all_results = []
        for x in results:
            all_results = all_results + x
        if not all_results or len(all_results) == 0:
            return list()
        all_results.sort(key=lambda k: k['start'])
        cur_max = None
        i = 0
        while i < len(all_results) and not cur_max:
            if self._post_check(all_results[i]):
                cur_max = all_results[i]
            i += 1

        if not cur_max:
            return res

        while i < len(all_results):
            x = all_results[i]
            i += 1
            if not self._post_check(x):
                continue
            if cur_max['end'] <= x['start']:
                parsed_date = self._parse_date(cur_max)
                if parsed_date:
                    if self._settings[EXTRACT_FIRST_DATE_ONLY]:
                        return res
                    res.append(parsed_date)
                cur_max = x
            else:
                if len(x['value']) > len(cur_max['value']):
                    cur_max = x
                elif len(x['value']) == len(cur_max['value']):
                    if x['order'] in ['SINGLE_YEAR']:
                        cur_max = x
                    elif len(x['order']) == len(cur_max['order']):
                        if len(x['groups']) < len(cur_max['groups']):
                            cur_max = x
                        elif len(x['groups']) == len(cur_max['groups']):
                            if sum(ele is not None for ele in x['groups']) < sum(ele is not None for ele in cur_max['groups']):
                                cur_max = x
                            elif self._settings[PREFER_LANGUAGE_DATE_ORDER] and self._lan in language_date_order:
                                if x['order'] == language_date_order[self._lan]:
                                    cur_max = x
                                elif x['order'] == self._settings[PREFERRED_DATE_ORDER]:
                                    cur_max = x
                            elif x['order'] == self._settings[PREFERRED_DATE_ORDER]:
                                cur_max = x
        parsed_date = self._parse_date(cur_max)
        if parsed_date:
            if self._settings[EXTRACT_FIRST_DATE_ONLY]:
                return res
            res.append(parsed_date)
        return res