old_contents: (function (window, Cryptoloji, undefined) {
    'use strict'
    
    Cryptoloji.states.credits = {
      enter: function () {
        $(".credits_section").addClass("section-show")
        $(".credits_section .mozilla_button").on("click", function(){
          Cryptoloji.stateman.go(Cryptoloji.stateman.previous.name)
        })
      },
      leave: function () {
        $(".credits_section").removeClass("section-show")
      }
    }
  
  })(window, window.Cryptoloji); 
  
new_contents: (function (window, Cryptoloji, undefined) {
    'use strict'
    
    Cryptoloji.states.credits = {
      enter: function () {
        $(".credits_section").addClass("section-show")
        $(".credits_section .mozilla_button").on("click", function(){
          var prev = Cryptoloji.stateman.previous.name
          if(prev){
            Cryptoloji.stateman.go(prev)
          } else {
            Cryptoloji.stateman.go("welcome")
          }
        })
      },
      leave: function () {
        $(".credits_section").removeClass("section-show")
      }
    }
  
  })(window, window.Cryptoloji); 
  
subject: fix logic credits back button