 
       details.name = name
 
-      details.dependencies = [] if not details.dependencies
+      details.dependencies ?= []
       details.aliases = []
 
       for dependency,i in details.dependencies

    fn = @commands[@command]

    throw new Error "Invalid argument" if typeof fn isnt "function"

    return fn.call this, (err) -> throw err if err


      log "Uploading tarball..."
      docker.buildImage tarball, options, (err, res) ->
        return done err if err

        res.pipe process.stdout

        res.on "end", ->
