code: public function offsetGet($offset)
      {
          $task = function() use ($offset) {
              $key = $this->getKey($offset);
              if(shm_has_var($this->id, $key)) {
                  return shm_get_var($this->id, $key);
              }
  
              return null;
          };
  
          return $this->lockExecute($task);
      }
docs: (PHP 5 &gt;= 5.0.0)<br/>
  Offset to retrieve
  @link http://php.net/manual/en/arrayaccess.offsetget.php
  
  @param mixed $offset <p>
  The offset to retrieve.
  </p>
  
  @return mixed Can return all value types.