Perl Style: Negative Array Subscripts

To get the last element in a list or array, use $array[-1] instead of $array[$#array]. The former works on both lists and arrays, but the latter does not.
Remember that substr, index, rindex, and splice also accept negative subscripts to count back from the end.
```
    split(@array, -2);   # pop twice
```
Remember substr is lvaluable:
```
    substr($s, -10) =~ s/ /./g;
```