code: public function offsetUnset($offset)
      {
          if (!$offset instanceof Date) {
              $offset = new Date($offset);
          }
  
          $index = $this->searchOffset($offset);
          unset($this->storage[$index]);
      }
docs: (PHP 5 &gt;= 5.1.0)<br/>
  Offset to unset
  @link http://php.net/manual/en/arrayaccess.offsetunset.php
  @param mixed $offset <p>
  The offset to unset.
  </p>
  @return void