def isSubtitle(self):
		val=False
		if self.__dict__['codec_type']:
			if str(self.codec_type)=='subtitle':
				val=True
		return val
L{defer.maybeDeferred} should let L{defer.Deferred} instance pass by
dataset/ETHPy150Open simonh10/ffprobe/build/lib/ffprobe/ffprobe.py/FFStream.isSubtitle--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/test_defer.py/DeferredTestCase.test_maybeDeferredAsyncError