def is_direct(self):
        return (
            (self.column_raw.count() == 1) and
            (self.column_mapped.count() == 1)
        )
L{Deferred}s can have callbacks that themselves return L{Deferred}s.
dataset/ETHPy150Open buildingenergy/buildingenergy-platform/seed/models.py/ColumnMapping.is_direct--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/test_defer.py/DeferredTestCase.test_nestedAsynchronousChainedDeferredsWithExtraCallbacks