# File lib/quiz1/t/solutions/Florian Gross/solitaire.rb, line 178 def decrypt(raw_text, keystream = nil, pretty = true) keystream ||= KeyStream.new text = clean(raw_text) result = "" 0.upto(text.size - 1) do |index| source_num = letter_to_number(text[index, 1]) key_num = letter_to_number(keystream.shift) result << number_to_letter((source_num - key_num) % 26) end result = pretty(result) if pretty return result end