cujo.js when, callbacks usage

callbacks.coffee

sumInForeSeconds = (a, b, callback) ->
            console.log "sumInFiveSeconds"
            setTimeout(()=>
                callback(a + b)
            , 4000)

sumInFiveSeconds = (a, b, callback) ->
            console.log "sumInFiveSeconds"
            setTimeout(()=>
                callback(a + b)
            , 5000)
            
sumPromise5 = callbacks.call(sumInFiveSeconds, 5, 10)
sumPromise4 = callbacks.call(sumInForeSeconds, 20, 7)

# When - instead of "when" (coffee compilator falls) 
When.join(sumPromise5, sumPromise4).then( (res)->
              console.log "RESULT": res
            , (err) ->
              console.log "ERROR", err
          )