years to extinction: This function takes a formatted countries DataFrame that has a Growth Rate column and adds a column labeled ' Years to Extinction'. Initialize the values in this column to np . nan: 2 Windows PowerShell X Service Growth Rate Years to Extinction Afghanistan 0. 380 26.26 NaN Albania 0. 579 9.89 NaN Algeria 0 . 298 12.53 NaN American Samoa NaN 19.19 NaN