These kind of bugs are common when Python multi-threading. What happens is that, on interpreter tear-down, the relevant module (myThread in this case) goes through a sort-of del myThread.
The call self.sample() is roughly equivalent to myThread.__dict__["sample"](self).
But if we're during the interpreter's tear-down sequence, then its own dictionary of known types might've already had myThread deleted, and now it's basically a NoneType - and has no 'sample' attribute.
