And actually other places, but let's just say theta does not equal negative pi over four. And we could think about all of this happening in some type of an open interval around negative pi over four if we wanted to get very precise. But if we, for this particular case, well let's just say everything we're doing is in the open interval. 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.