code: def database(db='', **kwargs):
      
      db = kwargs.pop('db', db)
      arg = db_config(db)
      arg.update(kwargs)
  
      return closing(MySQLdb.connect(**arg))
docs: usage:
      with database('my_db') as conn:
          c = conn.cursor()
          ....
      database 커넥션 with 문과 같이 사용하고, 알아서 close하기
      :param db: str: db스키마
      :param kwargs:
      :return: