code: def scalars_route(self, request):
      
      # TODO: return HTTP status code for malformed requests
      tag = request.args.get('tag')
      run = request.args.get('run')
      experiment = request.args.get('experiment')
      output_format = request.args.get('format')
      (body, mime_type) = self.scalars_impl(tag, run, experiment, output_format)
      return http_util.Respond(request, body, mime_type)
docs: Given a tag and single run, return array of ScalarEvents.