flask.ext.sqlalchemy is deperacated.
Without this, flask would keep throwing the deprecation warning
(.venv) naved:~/flask-warning/hil$ hil list_nodes all
/home/naved/flask-warning/hil/hil/model.py:14: ExtDeprecationWarning: Importing flask.ext.sqlalchemy is deprecated, use flask_sqlalchemy instead.
from flask.ext.sqlalchemy import SQLAlchemy