def txn():
index = random.randint(0, NUM_SHARDS - 1)
shard_name = "shard" + str(index)
counter = PLSimpleCounterShard.get_by_key_name(shard_name)
if counter is None:
counter = PLSimpleCounterShard(key_name=shard_name)
counter.count += value
counter.put()
