def average(self, projection=None):
        length = self.size()
        if projection:
            return sum(self.map(projection)) / length
        else:
            return sum(self) / length
Returns the user ID of the file's owner.
dataset/ETHPy150Open EntilZha/PyFunctional/functional/pipeline.py/Sequence.average--crossover with--dataset/ETHPy150Open nlloyd/SubliminalCollaborator/libs/twisted/python/filepath.py/FilePath.getUserID