"what function" is a correct and usable expression in written English.
You can use this expression whenever you are asking about the purpose of something. For example: "What function does this button serve?".
What function does it serve?
"I don't know what function that serves right now.
What function, then, would an account of laws now serve?
I didn't know why dessert was invented or what function it was meant to perform.
It is not quite clear what function all this overwrought writhing serves.
However, we're now primed to ask what function this gory tale is performing.
It is not known what function www.clintonemail.com ever served for Clinton.
What function did the Enola Gay serve in World War II? i.
Conclusion: I am still unable to determine what function I serve. . . .
Write an essay describing how guilds were formed, what function they served and in what form they exist today.
In the 21st century, it's by no means clear who the political parties represent or what function they serve.
