how to check if checkbox is checked

I added the code from the tutorial on this site to add an option to the design options of the row

https://siteorigin.com/docs/page-builder/hooks/custom-row-settings/

how do I check if the box is checked? I don’t see anything useful in the array of options

array(1) {
[“parallax”]=> array(5) {
[“name”]=> string(8) “Parallax”
[“type”]=> string(8) “checkbox”
[“group”]=> string(6) “design”
[“description”]=> string(61) “If enabled, the background image will have a parallax effect.”
[“priority”]=> int(8)
}
}