 The Modulo operator is a really useful arithmetic function that you can use in your code in order to iterate through a list endlessly. So one great use of this is you want to press a button and each time you press it you go between let's say three colors of neopixels, which is what I'm going to do here. Modulo is essentially A divided by B and the remainder is C. So in this case I have this counter. Every time I press this button, the counter increments by one. So you can see that going 35, 36. So 36 divided by 3, which is the size of this list I want to iterate to, goes in 12 times with a remainder of zero. So I'm going to use that zero as the first index in a list. The next time I increment this, we have a remainder of one. So three goes into 37, 12 times remainder of one. One more time, three goes into 38, 12 times remainder of two. The next time we go through this, hey, we're now back at a remainder of zero. So you can do that the sort of complex way. You can do that the nice easy way, which is what you see at the bottom there, 42. And then that percent sign actually means modulo. So 42 modulo three equals zero. Modulo three for 43 is one. And modulo three of 44 is two. And this goes on endlessly. The list here that you can see I'm using is this set of three colors, blue, magenta, and orange. There's the list. And so those are the items, zero, one, and two are blue, magenta, orange. So every time this button gets pressed, we just increment a by one. That's the counter. And then we run that modulo operation on the list value, which is this right here. So c, which is the index, is the answer to a modulo b. And so that is a way that you can use the mod operator in order to increment through a list inside of circuit python. And that is your circuit python parsec.