"If we allow people who *identify* as the opposing gender from what their anatomy implies, to use the restroom of the gender to which they identify as, it opens the door for any number of creepy dudes to follow a little girl into a womans restroom and eye her through the crack in the stall door, and when the police ask him about it, all he has to do is say "Oh, well I sexually identify myself as a woman, so i'm allowed to be in there."
Of course it would help if Americans stopped building restrooms where everyone can see everything. If there is a crack in the stall door that allows you to see anything but the occupant's feet you're doing it wrong.
// magically appears from somewhere
var result = await foo.CheckValidity(2000);
// timeout in ms
return "It's valid! Hooray!";
return "I can't be arsed to write code for all the cases. Something is wrong."
Never trust a computer you can't repair yourself.