What was the change in the net cash provided by (used for) by operating activities between 2018 and 2019?
{"Net cash provided by (used for): -- Operating activities": {"2019": 3752.6, "2018": 3748.3, "2017": 2925.6}, "Net cash provided by (used for): -- Investing activities": {"2019": -3987.5, "2018": -2749.5, "2017": -2800.9}, "Net cash provided by (used for): -- Financing activities": {"2019": 521.7, "2018": -607.7, "2017": -113.0}, "Net cash provided by (used for): -- Net effect of changes in foreign currency exchange rates on cash and cash equivalents, and restricted cash": {"2019": -13.7, "2018": -41.1, "2017": 6.7}, "Net cash provided by (used for): -- Net increase in cash and cash equivalents, and restricted cash": {"2019": 273.1, "2018": 350.0, "2017": 18.4}}
net_cash_2019 = df["Net cash provided by (used for): -- Operating activities"]["2019"]
net_cash_2018 = df["Net cash provided by (used for): -- Operating activities"]["2018"]
answer = net_cash_2019 - net_cash_2018