## Langton's ant

In this exercise, you will turn your buggle into a Langton's ant. These artificial little animals are very interesting because they are given simple rules that depend only on their local environment, and after a period of apparent chaotic behavior, a general pattern emerges.

The rules are absolutely trivial: to compute what the next step should be, you should check the current color of the ground (using `getGroundColor()`). If it's white, change it to black, turn right and move forward by one cell. If the ground is currently black, change it to white, turn left and move forward by one cell.

It's hard to come up with simpler rules isn't it? Well, let's go and code it now. You have to complete the `step()` method, which encodes the behavior of the ant at each step. You will probably use the `getGroundColor()` method to retrieve the color of the cell on which the ant is currently. Colors of interest are simply named `Color.black` and `Color.white`.

[!java]

To compare colors, you cannot use the equal signs (==), because these things are not scalar values but objects. Instead, you need to write something like the following:

    Color c /* = some initialization */;
    if (c.equals(Color.black)) {
      /* that's equal */
    } else {
      /* that was not equal */
    }

[/!]

Changing the ground color is not difficult, but a bit long: you have to change the brush color of your buggle, set the brush down (to mark the current cell -- with `brushDown()`), and set the brush back up (with `brushUp()`) to avoid further issues when the buggle will move. You are naturally free of organizing your code the way you want, but you may want to write a `setGroundColor(color)` method to factorize things a bit.

As you can see from the execution of this exercise, the interest in this algorithm is that after about 10000 steps of relative chaotic behavior, the ant start building a regular pattern. This emergence of a regular pattern from the chaos is rather fascinating, isn't it? Move on to the next exercise to see more of them.