public function __construct($length, $max_val, $min_val, $step, $units_before, $units_after)
{
parent::__construct($length, $max_val, $min_val, 1, false, $units_before, $units_after);
$this->step = $step;
}
public function __construct($length, $max_val, $min_val, $step, $units_before, $units_after, $decimal_digits, $label_callback)
{
// min_unit = 1, min_space = 1, fit = false
parent::__construct($length, $max_val, $min_val, 1, 1, false, $units_before, $units_after, $decimal_digits, $label_callback);
$this->step = $step;
}