RETRY: while (my $n_attempt=0, my $callsign=<>)
{
    $callsign =  uc($callsign); # uppercase
    $callsign =~ s/^\s*//;      # no leading spaces
    $callsign =~ s/\s*$//;      # no trailing spaces does chomp() also..
    next if $callsign eq "";    # skip NULL (blank lines)!
   
    my $callsign = (split(/,/,$callsign))[0]; #allow histogram format
                                              #w6oat,234 or just w6oat
                                             
    next if ($callsign =~ /^[a-zA-Z]\d{1}[a-zA-Z]$/); # like N7A 
    # NO PROCESSING OF 1X1 US CALLSIGNS!!!
   
    print STDERR "working on $callsign\n" if DEBUG;
    
    my $req = GET "http://www.qrz.com/xml?s=$key;callsign=$callsign";
    my $res = $ua->request($req);
   
    unless ($res->is_success)
    {
        $n_attempt++;
        print STDERR "$callsign ERROR: Try# $n_attempt of ".MAX_RETRY.
                     " err:". $res->status_line ."\n";
        sleep(1);
        redo RETRY if $n_attempt <= MAX_RETRY;
      
        print STDERR "$callsign ERROR: Try# $n_attempt of ".
                      MAX_RETRY." FAILED: ".
                      $res->status_line . "\n";  
                    
        next;   # skip this callsign and go to the next one.
                # This ain't gonna happen unless the QRZ server is
                # down. "if ($res->is_success)" means we got some kind
                # of response from the server. The QRZ server will
                # barf on about 1/2000 requests, hence the retries.                
    }