old_contents: const monk = require('monk')
  const url = 'localhost:27017/vuejs'
  const db = monk(url)
  
  console.log(db)
  
  db.then(() => {
      console.log('Connected correctly to server')
  })
  
  // db.createCollection("counters")
  // db.counters.insert({_id:"productid",sequence_value:1})
new_contents: const monk = require('monk')
  const url = 'localhost:27017/vuejs'
  const db = monk(url)
  
  db.then(() => {
      console.log('Connected correctly to server')
  })
  
  // 集合
  const collection = db.get('document')
  
  // db.createCollection("counters")
  // db.counters.insert({_id:"productid",sequence_value:1})
  
  collection.insert([{a: 1}, {a: 2}, {a: 3}])
  .then((docs) => {
    // docs contains the documents inserted with added **_id** fields
    // Inserted 3 documents into the document collection
  }).catch((err) => {
    // An error happened while inserting
  }).then(
      // () => db.close()
  )
subject: change list