Sometimes an invention comes along that makes so much sense you wonder why no one thought of it before.

You know the sort of thing. Skittle sorters. Head hammocks. Fried chicken taco shells. Half-and-half clocks. Okay, maybe not the last one. But one thing we absolutely need, in fact, one thing we've been crying out for, is an app to give you information on available toilet cubicles. See, you didn't realise it was a necessity, but now you're wondering how you ever went without it. According to the Japan Times, the new app - developed by KDDI Corp - will be offered to facilities owners from March this year. Offices will get first dibs, before the company takes its invention to sports stadiums and other public areas. It uses sensors to determine how many cubicles are free in public toilets in various buildings and sends the information to your smartphone, so you don't have to use your eyes and feet to walk in and check for yourself like an idiot. If you live in Japan and want to make your trips to public restrooms more efficient, urine luck. Plenty would have poo-pooed this idea in the past, but let's not get bogged down in the specifics. Okay, we'll stop now.