How to use promises for results instead of callbacks?

I’m trying to use ES7 async/await but this library uses callbacks. How can I transform this into a promise?

    this.db.findOne({
      property: 'abc'
    }, function(err, doc) {
    });

[dschissler]

I found the answer:

function findOne(db, opt) {
  return new Promise(function(resolve, reject) {
    db.findOne(opt, function(err, doc) {
      if (err) {
        reject(err)
      } else {
        resolve(doc)
      }
    })
  })
}

findOne(this.db, {
  abc: 123
}).then(function(doc) {
});

[dschissler]

Or with async/await:

doc = await findOne(this.db, {
  abc: 123
});