## 3. First program

As mentioned previously, there are two main windows used to interact with Reeborg. To the left is a program window; this is where you write the instructions for Reeborg to follow. To the right is the actual "graphical world" window in which Reeborg moves according to the instructions received.

Click on the Open Program button and select the file "move1.rur". (Note: dependings on the settings on your computer, you may or may not see the ".rur" extension.) You should see the following computer code, or code for short, appear in the program window.

    move()
    turn_off()

The word code is synonymous with "program text". A program is a series of instructions. In this case, the code consists of two instructions:

- `move()`: instructs Reeborg to move forward one "step".
- `turn_off()`: tells Reeborg that we have no more instructions to give him and that he can turn itself off, to save energy.

Reeborg recognizes instructions as commands that he must obey by the presence of two parentheses `()` which follow the words making up the instructions.

Now, click on the button and watch Reeborg move in his world.

### Your turn

Change the program by adding a second `move()` instruction as follows:

    move()
    move()
    turn_off()

Click on the Save button and give it the name "move2" (the program will automatically add the ".rur" extension). Congratulations! You have just created your first program. Now, ask Reeborg to execute or to run the program by clicking on the button.

### Experiment!

You can ask Reeborg to take more than two steps. What happens if you ask Reeborg to take so many steps that he has to move beyond the world boundary? In particular, look at the program window; you should have noticed by now that instructions are highlighted as they are being executed by Reeborg.

Reeborg explore its world; - - Dealing with eRRoRs