text: from flask import jsonify, request
  from flask_restx import Namespace, Resource
  from server import app, api
  from server.routes import prometheus
  from server.services import eval_service
  calc_namespace = Namespace('calculation', description='Simple Calculator')
  api.add_namespace(calc_namespace)
  @calc_namespace.route("")
  class Calculator(Resource):
      @api.param('expr', description='expression', type='string')
      @prometheus.track_requests
      def get(self):
          return jsonify({"result":eval_service.safe_eval(request.args.get("expr"))})