Ruby Rubbish

gistfile1.txt

```ruby
# Author: JR

isbn_in = IO.readlines( 'books.txt' );

isbn_in.each { |n|

	scan_digits = n.scan(/\d/)
	scan_filtered = scan_digits.join;

	correct_length = [10,13].include? scan_filtered.length

	puts "correct length: " + correct_length.to_s

	checksum_digit = scan_digits.pop

	puts "checksum digit: " + checksum_digit

	# This doesn't work
	checksum_calc = scan_digits.reduce { |sum, n| sum += n.to_i }

	puts 'checksum: ' + checksum_calc

	puts '--'
}
```