for my $key (keys %coll_key_hash) {
  foreach my $rec (@recs_read) {
    my @fields = split(/\|/, $rec);
    if ($fields[0] eq '010') {
      if ($fields[3] =~ $key) {
        $print_record = 1;
        if  ($key ne $prev_key) {
          $prev_key = $key;
          print_record ("CUST-BEG|$seq\n",' ');
        }
        print_record ("$rec\n",'c');
      }
      else {
          $print_record = 0;
      }
    }
    else {
      if ($print_record) {
          print_record ("$rec\n",'c');
      }
    }
  }
}

##</code><code>##

for my $key (keys %coll_key_hash){
	for my $rec (@recs_read){
		my @fields = split(/\|/, $rec);

		if($fields[0] eq '010'){
			$print_record = 0;
			if($fields[3] =~ $key){ #shouldn't this be /$key/ ?
				$print_record = 1;
				unless($key eq $prev_key){
					$prev_key = $key;
					print_record ("CUST-BEG|$seq\n",' ');
				}
			}
		}

		if($print_record){
			print_record ("$rec\n",'c');
		}
	}
}

##</code><code>##

for my $key (keys %coll_key_hash){
	for(my $recIdx = 0; $recIdx < scalar @recs_read; $recIdx++){
		#check, if redo overflowed the end of an array:
		next if(($recIdx + 1) > scalar @rec_read);

		my $rec = $recs_read[$recIdx];
		my @fields = split(/\|/, $rec);

		if($fields[0] eq '010'){
			$print_record = 0;
			if($fields[3] =~ $key){ #shouldn't this be /$key/ ?
				$print_record = 1;
				unless($key eq $prev_key){
					$prev_key = $key;
					print_record ("CUST-BEG|$seq\n",' ');
				}
			}
		}

		if($print_record){
			print_record ("$rec\n",'c');
			#Delete one record at the specified index:
			splice(@recs_read, $recIdx, 1);
			#Since the record at the current index is deleted, the new record shifted to the same index, so we test it again:
			redo;
		}
	}
}