Ex. q about the crazy effects of complements/substitutes on a wide range of goods:

"suppose a technological improvement has lowered the cost of manufacturing cell phone batteries. this would lead to an the supply of cell phones, causing the price of cell phones to because cell phones and landline telephones are this change in price would cause the demand for landline telephones to however, cell phones and cell phone applications are so the change in the price of cell phones would demand for cell phone applications."