调试第三方的wechat类，发现所有的第三方类引用时都需要添加"\",我很困惑，请大家指导一下这样写的原因。thinkphp版本3.2.3.
$weObj = new \Wechat($options);
$weObj->valid();
$type = $weObj->getRev()->getRevType();
switch($type) {
case \Wechat::MSGTYPE_TEXT:
$weObj->text("hello")->reply();
exit;
break;
case \Wechat::MSGTYPE_EVENT:
;
break;
case \Wechat::MSGTYPE_IMAGE:
;
break;
default: