Add summarize function to combiner (#5280)
Add summarize function to combiner (#5280)


cseed/hail,danking/hail,danking/hail,hail-is/hail,cseed/hail,hail-is/hail,hail-is/hail,cseed/hail,danking/hail,cseed/hail,hail-is/hail,danking/hail,cseed/hail,cseed/hail,cseed/hail,hail-is/hail,danking/hail,cseed/hail,danking/hail,danking/hail,hail-is/hail,danking/hail,hail-is/hail,hail-is/hail