text: (async () => {
      const { MongoClient } = require('mongodb')
      const client = new MongoClient(
          'mongodb://localhost:27017',
          {
              useNewUrlParser: true
          }
      );
      let ret = await client.connect();
      const test_db = client.db('test');
      const fruits = test_db.collection('fruits');
      ret = await fruits.insertOne({
          name: "芒果",
          price: 3.5
      });
      console.log('insert: ', ret);
  })();