Zend Framework致命错误：未捕获错误：调用未定义的函数_（）

Question

我有一个来自github的zend应用程序，当我尝试启动它时，我的导航器中出现此错误：

    p{
    font-family:"Trebuchet MS", Arial, Helvetica, sans-serif !important;
    color:#fff !important;
    font-size:14px !important;
    line-height:19px !important;
    margin-bottom:9px !important;
    text-decoration:none !important;
}

.each_cell{
  background:black;
  width:100%;
  height:39px;
  float:left;
  margin-bottom:3px;
}

.main_wrap {
    width:80%;
    background-color: #fff;
    border: solid 1px #a0b5ba;
    min-height: 100%;    
    height: 80vh;    
    overflow: auto;
    overflow-x: hidden;
    overflow-y: scroll;
    float:left;
    position: relative;
}

.left {
    background:red;
    width: 89px;
    text-align: center;
    position: absolute;
    z-index: 100;
}


.chatRooms{
    left:90px;
    width:100%;
    float:left;
    position: relative;
    overflow-x: scroll;
    white-space: nowrap;
}

.render_box{
  background:red;
  width:100px;
  height:20px;
  left:1500px;
  position:relative;
}

nav.phtml，第36行：

Fatal error: Uncaught Error: Call to undefined function _() in /Users/benjamin/Documents/Entreprise/c40/ddd/module/Application/view/layout/nav/nav.phtml:36 Stack trace: #0 /Users/benjamin/Documents/Entreprise/c40/ddd/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(506): include() #1 /Users/benjamin/Documents/Entreprise/c40/ddd/vendor/zendframework/zend-view/src/Helper/Partial.php(61): Zend\View\Renderer\PhpRenderer->render(NULL, NULL) #2 [internal function]: Zend\View\Helper\Partial->__invoke('header/guest') #3 /Users/benjamin/Documents/Entreprise/c40/ddd/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(397): call_user_func_array(Object(Zend\View\Helper\Partial), Array) #4 /Users/benjamin/Documents/Entreprise/c40/ddd/module/Application/view/layout/layout.phtml(129): Zend\View\Renderer\PhpRenderer->__call('partial', Array) #5 /Users/benjamin/Documents/Entreprise/c40/ddd/vendor/zendframework/zend-view/src/Renderer/PhpRenderer.php(506): include('/Users/benjamin...') #6 /Users/benjamin/Documents/Entrepr in /Users/benjamin/Documents/Entreprise/c40/ddd/module/Application/view/layout/nav/nav.phtml on line 36

有什么主意吗？ 谢谢