What is the purpose of "use curl --cookie with a file that doesn't exist"?

From https://curl.haxx.se/docs/httpscripting.html > Curl's "cookie engine" gets enabled when you use the --cookie option. > **If you only want curl to understand received cookies**, use --cookie > with a file that doesn't exist. Example, if you want to let curl > understand cookies from a page and follow a location (and thus > possibly send back cookies it received), you can invoke it like: > > curl --cookie nada --location http://www.example.com What is the purpose of "use --cookie with a file that doesn't exist"? What does "if you only want curl to understand received cookies" mean? Thanks.