docs: def add_routes(self, routes):
          '''Merges a Bottle application into this one.
  
          :param routes: A Bottle application or a sequence of routes.
          :type routes: :class:`bottle.Bottle` or `[bottle route]`.
          :rtype: :class:`WebBuilder`
          '''
          # Basically the same as `self.app.merge(routes)`, except this
          # changes the owner of the route so that plugins on `self.app`
          # apply to the routes given here.
          if isinstance(routes, bottle.Bottle):
              routes = routes.routes
          for route in routes:
              route.app = self.app
              self.app.add_route(route)
          return self