what is REQUEST_CHECK_SETTING?

I'm following this doc: https://developer.android.com/training/location/change-location-settings.html
REQUEST_CHECK_SETTING isn't defined but used, and I can't find its value after doing several searchs, all I found is that : What is the value of REQUEST_CHECK_SETTINGS?
someone giving it a "random" value (provided link not working), can someone please tell me how to get the value? or am I supposed to define it myself?
Thank you.