@@ -0,0 +1,650 @@
+%22%22%22Database%22%22%22%0A# pylint: disable=invalid-name%0A%0Aimport os%0A%0Afrom sqlalchemy import create_engine%0Afrom sqlalchemy.orm import scoped_session, sessionmaker%0A%0A%0Adb_url = os.environ.get('DATABASE_URL')%0Aif not db_url:%0A    raise Exception('%60DATABASE_URL%60 environment variable not set.')%0A%0Aengine = create_engine(db_url, echo=True)%0A%0Asession = scoped_session(sessionmaker(%0A    autocommit=False, autoflush=False, bind=engine))%0A%0A%0Adef create_tables():%0A    %22%22%22Create tables%22%22%22%0A    from todo.models import Base%0A    Base.metadata.create_all(bind=engine)%0A%0A%0Adef drop_tables():%0A    %22%22%22Drop tables%22%22%22%0A    from todo.models import Base%0A    Base.metadata.drop_all(bind=engine)%0A

add `database.py`