sub concat {
  my @s = @_    ; # strings
  my $max = $#s ; # last index
  # add extra tab to short strings except last one
  for my $n (0..$max-1){
    $s[$n] .= "\t" if (length($s[$n]) < 8);
  }
  return join "\t",@s; 
  # sub returns last expression 
  # evaluated so this works too
  # join "\t",@s; 
}