 ## evenSum

Author: Robert Baxter

Write a method `evenSum` that returns the sum of the values in even indices in a list of integers. Assume we are using a zero-based indexing where the first value in the list has index `0`, the second value has index `1`, and so on. The values in which we are interested in are the ones with even indices (the value at index `0`, the value at index `2`, the value at index `4`, and so on). For example, if a variable `list` stores the following sequence of values:

`[1, 18, 2, 7, 39, 8, 40, 7]`

Then the call of `list.evenSum();` should return the value `82` (`1 + 2 + 39 + 40`). Notice that what is important is the position of the numbers (index `0`, index `2`, index `4`, etc.), not whether the numbers themselves are even. If the list is empty, your method should return a sum of `0`.

Assume that we are adding this method to the `LinkedIntList` class as shown below. You may not call any other methods of the class to solve this problem and your method cannot change the contents of the list.

```    public class LinkedIntList {
private ListNode front;
...
}

public class ListNode {
public int data;
public ListNode next;
...
}
```