$this->input('?','action')
    ->isOneOf(array('search'));

$this->input('?','level')
    ->isOneOf(array('a','b','c'));

$this->input('?','query');

$this->input('?','page',1)
    ->isInt()
    ->setRange(1,null);

$this->input('?','count',10)
    ->isInt()
    ->setRange(5,50);