v3.1.0: simplified and changed process_input function API
v3.1.0: simplified and changed process_input function API (#1314) https://github.com/mlcommons/ck/issues/1313
v3.1.0: simplified and changed process_input function API (#1314) https://github.com/mlcommons/ck/issues/1313