What is the change in the total deferred tax assets from 2018 to 2019?
{"Stock-based compensation": {"2019": 25.9, "2018": 26.7}, "Research and development tax credit carryforwards": {"2019": 238.7, "2018": 170.3}, "Foreign tax credit carryforwards": {"2019": 198.6, "2018": 162.2}, "Accrued compensation and benefits": {"2019": 6.5, "2018": 25.9}, "Other accruals not currently deductible for tax": {"2019": 19.0, "2018": 22.9}, "Purchased technology and capitalized software": {"2019": 32.6, "2018": 43.4}, "Fixed assets": {"2019": 15.0, "2018": 16.5}, "Tax loss carryforwards": {"2019": 237.2, "2018": 85.7}, "Deferred revenue": {"2019": 49.0, "2018": 120.3}, "Other": {"2019": 28.4, "2018": 32.4}, "Total deferred tax assets": {"2019": 850.9, "2018": 706.3}, "Less: valuation allowance": {"2019": -797.8, "2018": -634.2}, "Net deferred tax assets": {"2019": 53.1, "2018": 72.1}, "Indefinite lived intangibles": {"2019": -67.6, "2018": -57.0}, "Total deferred tax liabilities": {"2019": -67.6, "2018": -57.0}, "Net deferred tax assets (liabilities)": {"2019": -14.5, "2018": 15.1}}
total_deferred_tax_assets_2019 = df["Total deferred tax assets"]["2019"]
total_deferred_tax_assets_2018 = df["Total deferred tax assets"]["2018"]
answer = total_deferred_tax_assets_2019 - total_deferred_tax_assets_2018