You're absolutely right. Once the coin has landed "heads" it has no chance of being "tails" - 0% probability. But I see your point, and I agree. But, its a common practice in the ball python world to advertise hets as "100%". So whether we like it or not, we have to consider it. Its kinda like the whole co-dominance vs incomplete dominance thing. Co-dominance is most likely not an accurate description of what we consider to be co-dominant traits in ball pythons. But it is so widely used, that we really can't avoid it.