code: def print_summary(self, stream=sys.stdout, indent=""):
          
          stream.write("%sTotal files      : %i\n" %
                       (indent, len(self.file_dict)))
          stream.write("%s  Input files    : %i\n" %
                       (indent, len(self.input_files)))
          stream.write("%s  Output files   : %i\n" %
                       (indent, len(self.output_files)))
          stream.write("%s  Internal files : %i\n" %
                       (indent, len(self.internal_files)))
          stream.write("%s  Temp files     : %i\n" %
                       (indent, len(self.temp_files)))
docs: Print a summary of the files in this file dict.
  
          This version explictly counts the union of all input and output files.