traitlets.py 文件源码

def cross_validation_lock(self):
        """
        A contextmanager for running a block with our cross validation lock set
        to True.

        At the end of the block, the lock's value is restored to its value
        prior to entering the block.
        """
        if self._cross_validation_lock:
            yield
            return
        else:
            try:
                self._cross_validation_lock = True
                yield
            finally:
                self._cross_validation_lock = False