I have a range as follows:

```
my_range =  [1297134..1328348, 1381732..1382716, 1406478..1408262, 1425452..1427966, 1607341..1609354, 1616388..1616625, 1844576..1846076, 1847450..1847672]

```

I like to loop through all these ranges and find the difference between the last range and the next first range, so for example:

```
1381732 - 1328348
1406478 - 1382716
etc..

```

I know there is the `first` and `last` methods but I have no idea how to state the the last range and the next first range.

Would appreciate some help.