Select Code to Download

use strict;
use warnings;
...
$str =~ s/(?<=[a-z])(?=[A-Z])|(?<=[?!.] )(?![a-z])/\n/g;

print $str;

The Tell-Tale Heart
Edgar Allen Poe
...
I heard many things in hell. 
How then am I mad? 
Hearken! and observe how healthily, how calmly, I can tell you the who
+le story.