old_contents: import os
  
  DEBUG = False
  RELOAD = False
  CSRF_ENABLED = True
  SECRET_KEY = 'notmysecretkey'
  SQLALCHEMY_DATABASE_URI = str(os.environ.get('HEROKU_POSTGRESQL', 'postgresql://localhost/myproddatabase'))
  
new_contents: import os
  
  DEBUG = False
  RELOAD = False
  CSRF_ENABLED = True
  SECRET_KEY = 'notmysecretkey'
  SQLALCHEMY_DATABASE_URI = str(os.environ.get('DATABASE_URL', 'postgresql://localhost/myproddatabase'))
  
subject: Change environment variable.