code: func (h *Client) PromotionAction(promotionAction string) *Client {
  	h.promotionAction = promotionAction
  	h.promotionActionSet = true
  	return h
  }
docs: // Specifies the role of the promotions included in a hit.
  // If a promotion action is not specified, the default promotion
  // action, 'view', is assumed. To measure a user click on a
  // promotion set this to 'promo_click'. For analytics.js the
  // Enhanced Ecommerce plugin must be installed before using
  // this field.