What was the change in the Prepaid rebates included in Other assets between 2018 and 2019?
{"Contract Assets -- Prepaid rebates included in Other current assets": {"2019": 64, "2018": 65}, "Contract Assets -- Prepaid rebates included in Other assets": {"2019": 1853, "2018": 999}, "Contract Assets -- Total Contract Assets": {"2019": 1917, "2018": 1064}, "Contract Liabilities -- Customer discounts and price concessions included in Accrued expenses and other liabilities": {"2019": -2070, "2018": -1656}, "Contract Liabilities -- Customer rights of return included in Accrued expenses and other liabilities": {"2019": -807, "2018": -325}, "Contract Liabilities -- Total Contract Liabilities": {"2019": -2877, "2018": -1981}}
prepaid_rebates_included_in_other_assets_2019 = df["Contract Assets -- Prepaid rebates included in Other assets"]["2019"]
prepaid_rebates_included_in_other_assets_2018 = df["Contract Assets -- Prepaid rebates included in Other assets"]["2018"]
answer = prepaid_rebates_included_in_other_assets_2019 - prepaid_rebates_included_in_other_assets_2018