This could actually be done in one line, but that line would be much longer than my screen is wide.
adjacent = [i for i in self.points if abs(point.x-i.x) < 0.1 and abs(point.y-i.y) < 0.1]
close_vert = [i for i in adjacent if abs(point.z-i.z) < self.thresh]
It just feels like I'm cheating.
