In which case the StreamNode has multiple output edges?

[徐涛]

Hi All,
        I am reading the source code of flink, when I read the StreamGraph 
generate part, I found that there is a property named outEdges in StreamNode. I 
know there is a case a StreamNode has multiple inEdges, but in which case the 
StreamNode has multiple outEdges?
        Thanks a lot.

Best
Henry