Pinq\Iterators\Common\Set::addRef PHP Method

    public function addRef(&$value)
    {
        $identityHash = Identity::hash($value);
        if (isset($this->values[$identityHash]) || array_key_exists($identityHash, $this->values)) {
            return false;
        }
        $this->values[$identityHash] =& $value;
        $this->length++;
        return true;
    }