```
for (i <- marker to cursor - 1 ){        
    if (buffer.charAt(i).isUpper){
        buffer.charAt(i).toString.toLowerCase
    } else if (buffer.charAt(i).isLower) {
        buffer.charAt(i).toString.toUpperCase
    }      
}

```

I've tried multiple methods to achieve but can't figure a solution and this is where I'm at. While trying other methods I used `slice` but couldn't get it to return a `Bool` for an `if` statement (Converted to a string but isUpper doesn't work on strings). Currently this does nothing to the strings, for context marker/cursor just highlight a selection on a sentence to invert.