Syntax: each (action {(v, k) ==> void})
Each method forces enumeration. To just add side-effect without enumerating, you can use {@link process} method.
Original LINQ method name: foreach.
public function each($action = null)
{
$action = Utils::createLambda($action, 'v,k', Functions::$blank);
foreach ($this as $k => $v) {
$action($v, $k);
}
}