My Python code runs successfully, but when imported as a module it gives 'cannot unpack non-iterable NoneType object'

Question

import os
import sys
import shutil
from src.logger import logging
from src.exception import CustomException

from dataclasses import dataclass

## intitialize the Data Ingestion configuration

@dataclass
class DataIngestionconfig:
    train_data_path:str=os.path.join('artifacts','train')
    test_data_path:str=os.path.join('artifacts','test')
    valid_data_path:str=os.path.join('artifacts','valid')

## create the data ingestion class

class DataIngestion:
    def __init__(self):
        self.ingestion_config=DataIngestionconfig()

    def initiate_data_ingestion(self):
        logging.info('Data Ingestion method starts')

        try:

            Train = os.path.join('notebooks\data\Train')
            print(Train)
            Test = os.path.join('notebooks\data\Test')

            def get_filenames(directory_path):
                filenames = [os.path.join(directory_path, filename) for filename in os.listdir(directory_path)]
                return filenames
            
            train_filenames = get_filenames(Train)
            test_filenames = get_filenames(Test)

            print(len(train_filenames))
            print(len(test_filenames))

            # Divide the train_filenames list into train and validation sets
            valid_filenames = train_filenames[50:]
            train_filenames = train_filenames[:50]

            logging.info('Split Data into Train and Validation')

            os.makedirs(self.ingestion_config.train_data_path, exist_ok=True)
            for filename in train_filenames:
                shutil.copy(filename, self.ingestion_config.train_data_path)

            os.makedirs(self.ingestion_config.test_data_path, exist_ok=True)
            for filename in test_filenames:
                shutil.copy(filename, self.ingestion_config.test_data_path)

            os.makedirs(self.ingestion_config.valid_data_path, exist_ok=True)
            for filename in valid_filenames:
                shutil.copy(filename, self.ingestion_config.valid_data_path)


            return(
                self.ingestion_config.train_data_path,
                self.ingestion_config.test_data_path,
                self.ingestion_config.valid_data_path

            )

        except Exception as e:
            logging.info('Exception occured at Data Ingestion Stage')
            raise CustomException(e,sys)

    

# if __name__ == '__main__':
#     obj = DataIngestion()
#     train_path, test_path, valid_path = obj.initiate_data_ingestion()
# print(train_path, test_path, valid_path)

whenever i'll run this code file i'll get my parameters

notebooks\data\Train
60
1
artifacts/train
artifacts/test
artifacts/valid

import os
import sys
import shutil
from src.logger import logging
from src.exception import CustomException

from src.components.data_ingestion import DataIngestion



if __name__=='__main__':
    obj = DataIngestion()
    train_path, test_path, valid_path = obj.initiate_data_ingestion()
    print(train_path,test_path,valid_path)

but when i'll use that as module i'll always get this

Traceback (most recent call last):
  File "d:\project\BMI\src\pipelines\training_pipeline.py", line 13, in <module>
    train_path, test_path, valid_path = obj.initiate_data_ingestion()
TypeError: cannot unpack non-iterable NoneType object

i have been stuck at this, can somebody solve this