#! /usr/perl/bin

use warnings;
use strict;

use Data::Dumper;
use warnings;
use strict;

my @charges = qw/ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch8 ch1 ch2
                 ch3 ch4 ch5 ch1 ch2 ch6 ch7 ch4 ch3 ch9 ch2 ch4/;

my %bundle1 = map { $_ => 0 } qw(ch3 ch4 ch6);

my $i;
for (@charges) {
    if (exists $bundle1{$_}) {
      $i++;
      if ($i == 3){
        print "chx ";
        $i = 0;
      }
    }
    else {
        print "$_ ";
    }
}
print "\n";

__END__
ch1 ch2 ch5 chx ch7 ch8 ch1 ch2 ch5 ch1 ch2 chx ch7 ch9 ch2 chx
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