old_contents: import os
  basedir = os.path.abspath(os.path.dirname(__file__))
  
  HOSTNAME = ''
  
  SQLALCHEMY_DATABASE_URI = "postgresql://postgres@localhost/url_shortener"
  SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')
  
new_contents: import os
  basedir = os.path.abspath(os.path.dirname(__file__))
  
  HOSTNAME = ''
  
  SQLALCHEMY_DATABASE_URI = os.environ['POSTGRESQL_DATABASE']
  SQLALCHEMY_MIGRATE_REPO = os.path.join(basedir, 'db_repository')
  
subject: update postgresql to get environment variable