fastify-riotjs-and-lowdb/node_modules/levelup/lib/promisify.js

function promisify () {
  var callback
  var promise = new Promise(function (resolve, reject) {
    callback = function callback (err, value) {
      if (err) reject(err)
      else resolve(value)
    }
  })
  callback.promise = promise
  return callback
}

module.exports = promisify