{  # create a scoping block for slurp-mode reading
   local $/ = undef;
   my $str = <>;

   my $bgnstr = "#:lav\n";
   my $bgnlen = length( $bgn );
   my $endstr = "#:eof\n";

   while ( my $startpos = index( $str, $bgnstr ) >= 0 ) {
       $startpos += $bgnlen;
       my $stoppos = index( $str, $endstr, $startpos );
       $stoppos = length( $str ) if ( $stoppos < 0 );
       my $val = substr( $str, $startpos, $stoppos - $startpos );
       print $val;
       $str = substr( $str, $stoppos );
   }
}