code: def check_args(cls, config, options, args, parser, package_file=None):
          
          if not args:
              parser.error("no input files specified")
          if not (package_file or options.package_file):
              parser.error("no package file specified")
          if not options.entry_point_process:
              parser.error("no entry point process specified")
docs: Override in subclass if required.