Some of the input YANG modules may not contain data nodes (e.g. type definitions). Some other YANG modules may define data nodes, but be used as augmentation. As the number of input YANG files typically does not match the number of output files, the generator should report how each input file was processed and provide the total number of input files and the total number of output files. I'd suggest to produce the total count as normal output and the detailed description per file as verbose (logging) output.