|(quoted from I Had to Call In a Mathematician)|
“Hi Janice. It's Mort. I've got another problem here and I've had to call in a mathematician. I'm stuck at home until she's done.”
The mathematician came over with a sheet of paper.
“It looks like someone was trying to use a contraction mapping here. That won't work unless the target space is compact.”
“Oh, ah, I wonder how that got in there. One of the kids, maybe.” She rolled her eyes like I was an idiot.
“I'm not sure if this space is separable. Where did you get it?”