

def _reader(self, allow_async=False):
    if (self.mode is None):
        self.mode = _READER
    elif ((self.mode is _ASYNC_READER) and (not self)):
        raise TypeError("Can't upgrade an ASYNC_READER transaction to a READER mid-transaction")

dataset/ETHPy150Open openstack/oslo.db/oslo_db/sqlalchemy/enginefacade.py _TransactionContext._reader/VarMisuse@44/56 `allow_async`->`self`