text: from sqlalchemy import create_engine
  from sqlalchemy.orm import scoped_session, sessionmaker
  from sqlalchemy.ext.declarative import declarative_base
  import os
  
  db_uri = 'postgresql+psycopg2://%s:%s@%s:%s/%s' % (
      # ARGS.dbuser, ARGS.dbpass, ARGS.dbhost, ARGS.dbname
      os.environ.get('DBUSER', 'bety'),
      os.environ.get('DBPASS', 'bety'),
      os.environ.get('DBHOST', 'localhost'),
      os.environ.get('DBPORT', '5432'),
      os.environ.get('DBNAME', 'bety')
  )
  
  # add echo=True to see actual queries executed
  engine = create_engine(db_uri, convert_unicode=True)
  
  db_session = scoped_session(sessionmaker(autocommit=False,
                                           autoflush=False,
                                           bind=engine))
  
  def get_engine():
      return engine
  #Base = declarative_base()
  #Base.query = db_session.query_property()
  
  #def init_db():
  #    # import all modules here that might define models so that
  #    # they will be registered properly on the metadata.  Otherwise
  #    # you will have to import them first before calling init_db()
  #    import yourapplication.models
  #    Base.metadata.create_all(bind=engine)
  