What was the change in the Gross increases - prior period tax positions from 2018 to 2019?
{"Unrecognized tax benefit - beginning of period": {"2019": 10321, "2018": 9346, "2017": 7687}, "Gross increases - prior period tax positions": {"2019": 98, "2018": 729, "2017": 712}, "Gross decreases - prior period tax positions": {"2019": -88, "2018": -878, "2017": -691}, "Gross increases - current period tax positions": {"2019": 1302, "2018": 1124, "2017": 1638}, "Unrecognized tax benefit - end of period": {"2019": 11633, "2018": 10321, "2017": 9346}}
gross_increases__prior_period_tax_positions_2019 = df["Gross increases - prior period tax positions"]["2019"]
gross_increases__prior_period_tax_positions_2018 = df["Gross increases - prior period tax positions"]["2018"]
answer = gross_increases__prior_period_tax_positions_2019 - gross_increases__prior_period_tax_positions_2018