To take advantage of these capabilities, a variable will be needed. A variable, as the name suggests, is a program element that allows an attribute to be varied.

Begin by creating a variable that specifies the number of the LED addressed. Select the Make a Variable option under the Data & Blocks section of the Scripts tab.

Then enter the name “LED” in the New Variable dialog box that appears.

Then create a program with the following steps (as shown in the figure below).

1. Set LED to 1
2. Repeat 30
   1. Turn On LED
   1. Change LED by 1

The Repeat block is found under the Control category of the Scripts tab.

This program initially sets the LED variable to 1. Then it repeats the following steps thirty times:

            Turn On LED 1

            Increase the LED variable by 1 (making its value 2).

            Turn On LED 2

            Increase the LED variable by 1 (making its value 3)

            Etc.

A program that repeats an action in this manner is called a loop. If this program were written out line by line, thirty lines of code would be required to turn on all of the LEDs. The use of a variable combined with a loop allows this action to be accomplished with just a couple of lines of code.

Once it has been verified that the code works, it can be saved for re-use at a later date by defining a new block, All_On. The term function is used to refer to a block of code that has been defined in this fashion.