my $fs4 = {'_structure' => {}};
 say (exists $fs4->{_structure}{'/Users/dotfiles/perl5/my_modules'}{BLAH}{Crap});
 d $fs4->{_structure}, 3;

##</code><code>##

$VAR1 = {
  '/Users/dotfiles/perl5/my_modules' => {
    'BLAH' => {}
  }
};