What is the difference in the high and low sale of the first quarter in 2019?
{"2019 -- First Quarter": {"High Sale": 8.95, "Low Sale": 7.3}, "2019 -- Second Quarter": {"High Sale": 11.38, "Low Sale": 7.8}, "2019 -- Third Quarter": {"High Sale": 13.38, "Low Sale": 9.6}, "2019 -- Fourth Quarter": {"High Sale": 13.52, "Low Sale": 10.8}, "2018 -- First Quarter": {"High Sale": 10.76, "Low Sale": 7.91}, "2018 -- Second Quarter": {"High Sale": 10.0, "Low Sale": 7.53}, "2018 -- Third Quarter": {"High Sale": 9.94, "Low Sale": 8.66}, "2018 -- Fourth Quarter": {"High Sale": 10.59, "Low Sale": 8.55}}
high_2019 = df["2019 -- First Quarter"]["High Sale"]
low_2019 = df["2019 -- First Quarter"]["Low Sale"]
answer = high_2019 - low_2019