 ## BJP5 Exercise 16.6: hasTwoConsecutive

Author: Whitaker Brand (on 2019/09/19)

Write a method `hasTwoConsecutive` that returns whether or not a list of integers has two adjacent numbers that are consecutive integers (`true` if such a pair exists and `false` otherwise). For example, if a variable `list` stores the following sequence of values, then the call `list.hasTwoConsecutive()` should return `true` because the list contains the adjacent numbers (7, 8) which are a pair of consecutive numbers:

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

If the list had stored the following sequence of values, then the method should return `false`:

```[1, 18, 17, 2, 7, 39, 18, 40, 8]
```

This sequence contains some pairs of numbers that could represent consecutive integers (e.g., 1 and 2, 7 and 8, 39 and 40), but those pairs of numbers are not adjacent in the sequence. The list also has a pair of adjacent numbers (18, 17) that are not in the right order to be considered consecutive. You may not make any assumptions about how many elements are in the list.

Assume that you are adding this method to the `LinkedIntList` class as defined below:

```public class LinkedIntList {
private ListNode front;   // null for an empty list
...
}
```