code: def verify(opts):
      
      resources = _load(opts.resources, opts.output_dir)
      if opts.all:
          opts.resource_names = ALL
      invalid = _invalid(resources, opts.resource_names)
      if not invalid:
          if not opts.quiet:
              print("All resources successfully downloaded")
          return 0
      else:
          if not opts.quiet:
              print("Invalid or missing resources: {}".format(', '.join(invalid)))
          return 1
docs: Verify that one or more resources were downloaded successfully.