# File lib/quiz1/t/solutions/Niklas Frykholm/solitaire.rb, line 107
  def process(s, &combiner)
    s = sanitize(s)
    out = ""
    s.each_byte { |c|
      if c >= ?A and c <= ?Z
        key = @keystream.get
        res = combiner.call(c, key[0])
        out << res.chr
      else
        out << c.chr
      end
    }
    return out
  end