splice @list_words, 10; # inspect only the first 10 elements

use Data::Dumper;
local $Data::Dumper::Useqq = 1; # output strings with whitespace characters escaped

while (scalar @list_words) {
  test_if_letters_are_included();

  foreach(@list_words) {
    print "list_words:<$_>\n";
    print Dumper $_; # also show the string with whitespace escaped
  }
  my @array = qw(this that the other thing);
  print "@array";
  #say "@list_words";
  say scalar @list_words;
}