closures.js

function processOneStuff(whateverFunction) {
  return function (oneStuff, cb) {
    whateverFunction(oneStuff, function (err, res) {
      cb(err, res);
    })
  }
}

module.exports = function processManyStuffs(manyStuffs, someFunction, cb) {
  
  async.map(manyStuffs, processOneStuff(someFunction), function (err, res) {
    cb(err, res);
  })
  
}