public function input()
{
$value = func_get_arg(0);
$input = parent::input($value);
$input->replaceClass('radio', 'checkbox');
$input->attr(array('name' => $this->name() . '[]', 'type' => 'checkbox', 'value' => $value, 'checked' => in_array($value, (array) $this->value())));
return $input;
}