@abstractmethod
    def typeof(self, scheme, state_scheme):
Provides a simple mechanism for starting a transaction based on the
dataset/ETHPy150Open uwescience/raco/raco/expression/expression.py/Expression.typeof--crossover with--dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/Paste-2.0.1/paste/transaction.py/BasicTransactionHandler