old_contents: import datetime
  import os
  basedir = os.path.abspath(os.path.dirname(__file__))
  
  
  if os.environ.get('DATABASE_URL') is None:
      SQLALCHEMY_DATABASE_URI = ('sqlite:///' + os.path.join(basedir, 'app.db') +
                                 '?check_same_thread=False')
  else:
      SQLALCHEMY_DATABASE_URI = os.environ['DATABASE_URL']
  SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')
  SQLALCHEMY_RECORD_QUERIES = True
  
  ADMINS = ['you@example.com']
  
  
  class Config(object):
      DEBUG = False
      TESTING = False
      CSRF_ENABLED = True
      WTF_CSRF_ENABLED = True
      SECRET_KEY = 'you-will-never-guess'
      sessionTimeout = datetime.timedelta(minutes=-2)
  
      SQLALCHEMY_ECHO = False
      SQLALCHEMY_DATABASE_URI = SQLALCHEMY_DATABASE_URI
      SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')
  
  
  class DevelopmentConfig(Config):
      DEBUG = True
      SQLALCHEMY_ECHO = True
      SQLALCHEMY_RECORD_QUERIES = True
  
  
  class TestingConfig(Config):
      TESTING = True
  
new_contents: import os
  basedir = os.path.abspath(os.path.dirname(__file__))
  
  
  if os.environ.get('DATABASE_URL') is None:
      SQLALCHEMY_DATABASE_URI = ('sqlite:///' + os.path.join(basedir, 'app.db') +
                                 '?check_same_thread=False')
  else:
      SQLALCHEMY_DATABASE_URI = os.environ['DATABASE_URL']
  SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')
  SQLALCHEMY_RECORD_QUERIES = True
  
  ADMINS = ['you@example.com']
  
  
  class Config(object):
      DEBUG = False
      TESTING = False
      CSRF_ENABLED = True
      WTF_CSRF_ENABLED = True
  
      SQLALCHEMY_ECHO = False
      SQLALCHEMY_DATABASE_URI = SQLALCHEMY_DATABASE_URI
      SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')
  
  
  class DevelopmentConfig(Config):
      DEBUG = True
      SQLALCHEMY_ECHO = True
      SQLALCHEMY_RECORD_QUERIES = True
  
  
  class TestingConfig(Config):
      TESTING = True
  
subject: make session key dynamic