So in open interval, in open interval between theta, or say negative one and one. And I think that covers it, because if we have pi over four, that is not going to get us the zero over zero form. And pi over four would make this denominator equal to zero, and it also makes, let's see, pi over four also will make this denominator equal to zero. Because we would get one minus one. So I think we're good if we're just assuming, if we're restricting to this open interval, and that's okay because we're taking the limit and say it approaches something within this open interval. And I'm being extra precise, because I'm trying to explain it to you, and it's important to be precise. But obviously if you're working this out on a test or notebook, you wouldn't be taking, or taking as much trouble to be putting all of these caveats in.