The user needs to specify the Flask application instance in the gunicorn command. Look at the main Python file (e.g., app.py or run.py) in the proxy pool repository to find the Flask app variable (commonly named 'app' or 'application'). The correct format is 'module:variable' where 'module' is the filename without .py. For example, if the app is in app.py and the variable is 'app', the command would be 'gunicorn w 2 b 127.0.0.1:5000 app:app'. Provide this to the user.
