What was the change in total revenue between 2018 and 2019?
{"Total revenue": {"January 31, 2020": 777.0, "February 1, 2019": 639.0, "February 2, 2018": 474.0}, "Operating income": {"January 31, 2020": -287.0, "February 1, 2019": -247.0, "February 2, 2018": -239.0}, "Net income": {"January 31, 2020": -204.0, "February 1, 2019": -832.0, "February 2, 2018": -234.0}, "Net income attributable to VMware": {"January 31, 2020": -148.0, "February 1, 2019": -772.0, "February 2, 2018": -222.0}, "Net income per weighted-average share attributable to VMware common stockholders, basic for Classes A and B": {"January 31, 2020": -0.63, "February 1, 2019": -1.95, "February 2, 2018": -0.56}, "Net income per weighted-average share attributable to VMware common stockholders, diluted for Classes A and B": {"January 31, 2020": -0.67, "February 1, 2019": -1.93, "February 2, 2018": -0.56}, "Other comprehensive income (loss)": {"January 31, 2020": "$\u2014", "February 1, 2019": -26.0, "February 2, 2018": 35.0}}
total_revenue_february_1_2019 = df["Total revenue"]["February 1, 2019"]
total_revenue_february_2_2018 = df["Total revenue"]["February 2, 2018"]
answer = total_revenue_february_1_2019 - total_revenue_february_2_2018