import function from a file in the same folder

I'm building a Flask app with Python 3.5 following a tutorial, based on different import rules. By looking for similar questions, I managed to solve an ImportError based on importing from a nested folder by adding the folder to the path, but I keep failing at importing a function from a script in the same folder (already in the path). The folder structure is this: ``` DoubleDibz ├── app │ ├── __init__.py │ ├── api │ │ ├── __init__.py │ │ └── helloworld.py │ ├── app.py │ ├── common │ │ ├── __init__.py │ │ └── constants.py │ ├── config.py │ ├── extensions.py │ ├── static │ └── templates └── run.py ``` In app.py I import a function from config.py by using this code: ``` import config as Config ``` but I get this error: ``` ImportError: No module named 'config' ``` I don't understand what's the problem, being the two files in the same folder.