def sign(params)
      raise "Something's wrong; @secret is nil" if @secret.nil?
      sign_me = @secret
      params.keys.sort.each do |key|
        sign_me += key
        raise "Omit params with nil values; key #{key} was nil" if params[key].nil?
        sign_me += params[key]
      end
      return Digest::MD5.hexdigest(sign_me)
    end
def sign(params)
      raise "Something's wrong; @secret is nil" if @secret.nil?
      sign_me = @secret
      params.keys.sort.each do |key|
        sign_me += key
        raise "Omit params with nil values; key #{key} was nil" if params[key].nil?
        sign_me += params[key]
      end
      return Digest::MD5.hexdigest(sign_me)
    end
Signs the request given the params and secret key

 [params] hash of parameters