对于输入PCollection，求其所有包含元素相加的结果 Args: pcollection (PCollection): 输入PCollection **options: 可配置参数 Returns: PObject: 表示结果的PObject >>> from bigflow import transforms >>> _p = _pipeline.parallelize([1, 2, 3, 4]) >>> transforms.sum(_p).get() 10
(pcollection, **options)