How to select the 3 last dates in Python

Question

I have a dataset that looks like his:

ID date
1  O1-01-2012
1  05-02-2012
1  25-06-2013
1  14-12-2013
1  10-04-2014
2  19-05-2012
2  07-08-2014
2  10-09-2014