def __setitem__(self, key, value):
        try:
            dialect, value_key = self._key(key)
        except __HOLE__:
            raise exc.ArgumentError(
                "Keys must be of the form <dialectname>_<argname>")
        else:
            self.obj.dialect_options[dialect][value_key] = value
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/sql/base.py/_DialectArgView.__setitem__