{
   package Reader;

   sub new {
      my ($class, $fh) = @_;
      my $self = bless([$fh, undef]);
   }

   sub get_line {
      my ($self) = @_;

      our $fh;  local *fh  = \($self->[0]);
      our $buf; local *buf = \($self->[1]);

      if (!defined($fh)) {
         return undef;
      }

      if (!defined($buf)) {
         for (;;) {
            my $line = <$fh>;

            if (!defined($line)) {
               undef $fh;
               return undef;
            }

            if ($line =~ /^\d\d:\d\d:\d\d /) {
               $buf = $line;
               last;
            }
         }
      }

      for (;;) {
         my $line = <$fh>;

         if (!defined($line)) {
            undef $fh;
            return "$buf\n";
         }

         if ($line =~ /^\d\d:\d\d:\d\d /) {
            return ((undef, $buf) = ($buf, $line))[0];
         }

         chomp($buf);
         $buf .= $line;
      }
   }
}