code: def update email, card_or_token = nil
        attributes = self.class.attributes - [:token, :created_at]
        options    = self.class.parse_options_for_request(attributes, email: email, card: card_or_token)
        response   = self.class.put(URI.parse(PinPayment.api_url).tap{|uri| uri.path = "/1/customers/#{token}" }, options)
        self.email = response['email']
        self.card  = response['card']
        self
      end
docs: Update a customer using the pin API.
  
   @param [String] email the customer's new email address
   @param [String, PinPayment::Card, Hash] card_or_token the customer's new credit card details
   @return [PinPayment::Customer]