def _union(rdd: RDD, other: RDD, func):
num_partition = max(rdd.getNumPartitions(), other.getNumPartitions())
def _func(pair):
iter1, iter2 = pair
val1 = list(iter1)
val2 = list(iter2)
if not val1:
return val2[0]
if not val2:
return val1[0]
return func(val1[0], val2[0])
return _map_value(rdd.cogroup(other, num_partition), _func)
