This section seems to cause issues with cutting away the last "m" of ansi characters whenever they are the very last character of a string. The result of printing `code_indexes` and `char_indexes` before and after this fix:
```python
ANSIString("{gtest{n")
>>> before end fix: code: [0, 1, 2, 3, 4, 5, 6, 7, 8, 13, 14, 15, 16], char: [9, 10, 11, 12]
<<< after end fix: code: [0, 1, 2, 3, 4, 5, 6, 7, 8, 13, 14, 15] char: [9, 10, 11, 12, 16]
```
The end fix adds the last character (index 16) to the `char_indexes` list. I would remove it but I'm not sure what this will break and in what "instances" (as the comment string mentions) this fixes some other bug.