code: public function get($key)
      {
          $Obj = $this->getRaw($this->buildKey($key));
          if ($Obj instanceof TagcacheObj) {
              $Data = $Obj->getVar($this);
              if ($Data === false) {
                  $this->delete($key);
              }
  
              return $Data;
          }
  
          return $Obj;
      }
docs: get cache
  @param  string $key
  @return mixed