class UserAgent::Version

def <=>(other)
  case other
  when Version
    if @comparable
      to_a.zip(other.to_a).each do |a, b|
        if b.nil?
          return -1
        elsif a.nil?
          return 1
        elsif a.is_a?(String) && b.is_a?(Integer)
          return -1
        elsif a.is_a?(Integer) && b.is_a?(String)
          return 1
        elsif a == b
          next
        else
          return a <=> b
        end
      end
      0
    else
      to_s == other.to_s ? 0 : nil
    end
  when String
    self <=> self.class.new(other)
  else
    raise ArgumentError, "comparison of Version with #{other.inspect} failed"
  end
end