I'm new to python. I have this code. I need to get a result as a json from postoffices, but it only tells that I don't have problems in my code like "Process finished with exit code 0". When I'm trying to `print(get_settlement_postoffices())`, it gives me the same answer.

```
from __future__ import annotations

from datetime import datetime
import json
from typing import TYPE_CHECKING, List, Optional, Union

from pochta.enums import PostofficeWorkType
from pochta.utils import HTTPMethod

class Services:
    def get_settlement_postoffices(self, settlement: str,
                                   region: Optional[str] = None,
                                   district: Optional[str] = None) -> List[str]:

        url = '/postoffice/1.0/settlement.offices.codes'

        params = {
            'settlement': settlement,
            'region': region,
            'district': district,
        }

        res = self._client.request(HTTPMethod.GET, url, params=params)
        return res.json()

```

I want to get an array with postal codes of a city I've chosen in a settlement param.