Select Code to Download

  my $re_langs = sprintf '(?:%s)', join '|', keys %validLanguages;

  $text =~ /^(?:$re_langs|\s|,)*\z/;

  $text =~ /^(?:$re_langs(?=\s|,|\z)|\s|,)*\z/;

  $text =~ /^(?:$re_langs\b|\s|,)*\z/;

  $text =~ m{
    ^
...
    )*
    \z
  }x;

  $text =~ m{
    ^
...
      )
    )* \z
  }x;

  $text =~ /^\s*(?:$re_langs\s*(?:,\s*|\z))*\z/;