code: def test_postal_code_normalization():
      df = pd.DataFrame(
          {"postal_code": ["  0ab-0123 ", "0123  3948  "]}
      )
      dataset = Dataset("test321", df=df)  # type: ignore
      dataset.meaning_types = {
          "postal_code": FileColumnMeaningType.POSTAL_CODE
      }
      dataset._Dataset__normalize_postal_code()
      assert dataset.data.loc[0, "postal_code"] == "AB0123"
      assert dataset.data.loc[1, "postal_code"] == "1233948"
  
imports: import ipaddress
  import random
  from datetime import date, datetime
  import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
  from upgini import Dataset, FileColumnMeaningType
  from upgini.errors import ValidationError
  from upgini.metadata import ModelTaskType, SearchKey
  from upgini.resource_bundle import bundle
  from upgini.utils.datetime_utils import DateTimeSearchKeyConverter
  from upgini.utils.email_utils import EmailSearchKeyConverter
  from upgini.utils.features_validator import FeaturesValidator
  from upgini.utils.warning_counter import WarningCounter
label_desc: Use image node_id 17 for calling a global function with example usage: test_postal_code_normalization() without return types