```
function check_login(){
    var authenticated  = false;
    $.ajax({type:"POST",url:"/account/islogin/",data:"",async:"false",
        success:function(data){
            if(data=="null"){
                signup();
                authenticated =  false;
            }
            authenticated =  true;   
        }
    });
    return authenticated;
};

```

why the function always return `false`,even `authenticated=true` is executed.