/**
* Prepends value as element to set.
*
* @param type $value
* @return type prepended value
*/
public function unshift($value)
{
if (is_array($value)) {
$value = $this->filterByType($value, false);
} else {
if (!is_null($value) && !$this->isMatchingType($value)) {
throw new \InvalidArgumentException('invalid type of value');
}
}
return parent::unshift($value);
}
