If they have step functions, you can break up the larger integral into smaller integrals. You'll also see that this is useful when we prove the fundamental theorem of calculus. So in general, this is actually a very, very, very useful technique. Let me actually draw an integral where it might be very useful to utilize that property. So if this is a, this is b, and let's say the function, I'm just going to make it constant over an interval. So it's constant from there to there, and then it drops down from there to there. Let's say the function looked like this.