text: from sqlalchemy import create_engine
  from sqlalchemy.orm import scoped_session, sessionmaker
  from sqlalchemy.ext.declarative import declarative_base
  import os
  from config import Cfg
  
  cfg = Cfg()
  dir_path = os.path.dirname(os.path.realpath(__file__))
  if cfg.testnet:
      engine = create_engine("sqlite:///%s/gethtxscan_testnet.db" % dir_path, convert_unicode=True)
  else:
      engine = create_engine("sqlite:///%s/gethtxscan.db" % dir_path, convert_unicode=True)
  db_session = scoped_session(sessionmaker(autocommit=False,
                                           autoflush=False,
                                           bind=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 models
      Base.metadata.create_all(bind=engine)
  