docs: def auth_basic(check, realm="private", text="Access denied"):
      ''' Callback decorator to require HTTP auth (basic).
          TODO: Add route(check_auth=...) parameter. '''
      def decorator(func):
          def wrapper(*a, **ka):
              user, password = request.auth or (None, None)
              if user is None or not check(user, password):
                  err = HTTPError(401, text)
                  err.add_header('WWW-Authenticate', 'Basic realm="%s"' % realm)
                  return err
              return func(*a, **ka)
          return wrapper
      return decorator