@tech_userreport.com/queue

Simple command queue, so callbacks enqueued are called one after another.

``coffee
queue = require "@tech_userreport.com/queue"

cmdq = queue()

cmdq.enqueue (next) ->
setTimeout () ->
console.log "I'll be called first"
next()
, 0

cmdq.enqueue (next) ->
console.log "I'll be called second"
next()
`

$3

Enqueue command to be called. Receiving callback which
should be called once command is finished.

`coffee
cmdq.enqueue (next) ->
longRunningAsyncMethod () ->
next()
`

$3

Count of commands in queue including one being executed

`coffee
cmdq.enqueue (next) ->
console.log cmdq.length # 1
next()
`

$3

Subscribe to changes in queue. It's called when new
command is added to queue or command had finished
execution.

`coffee
cmdq.onchange () ->
# called two times
# first call .length is 1
# second call .length is 0
console.log cmdq.length

cmdq.enqueue (next) ->
next()
`

$3

Pause queue processing.

`coffee
queue = require "@tech_userreport.com/queue"

cmdq1 = queue()
cmdq2 = queue()

cmdq1.onchange () ->
if cmdq1.length isnt 0
cmdq2.pause()
else
cmdq2.resume()

``

$3

Resume queue processing