JQuery :: How To Check If Template Already Compiled

Is it possible to check if template is already compiled and in the stack? For example I need a boolean check, to decide to make ajax call for template or pick it from compiled stack.
var callback = fucntion(template){do stuff...}
var template = $.tmpl('thumbnail',data);
if(!template) {do ajax and get template, then use callback}
else{
callback(template);
}
This would be great, but it doesn't work. $.tmpl doesn't return false if template isn't compiled and in stack.