<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _list_records(self, rtype=None, name=None, content=None):
 """List all records. record_type, name and content are used to filter the records. If possible it filters during the query, otherwise afterwards. An empty list is returned if no records are found. """


        filter_query = {}
        if rtype:
            filter_query["record_type"] = rtype
        if name:
            name = self._relative_name(name)
            filter_query["name"] = name
        payload = self._get(
            "/v1/domains/{0}/records".format(self.domain),
            query_params=filter_query,
        )

        records = []
        for data in payload:
            record = data["record"]

            if content and record["content"] != content:
                continue

            if record["name"] == "":
                rname = self.domain
            else:
                rname = ".".join((record["name"], self.domain))

            processed_record = {
                "type": record["record_type"],
                "name": rname,
                "ttl": record["ttl"],
                "content": record["content"],
                "id": record["id"],
            }
            if record["prio"]:
                processed_record["options"] = {
                    "mx": {"priority": record["prio"]}
                }
            records.append(processed_record)

        LOGGER.debug("list_records: %s", records)
        return records