import icalendar
import icalendar.tools
import datetime
t = icalendar.Todo()
t['uid'] = icalendar.tools.UIDGenerator().uid(host_name='watdo')
t.add('completed', datetime.datetime.now())
print(t['completed'])  # vDDDTypes
t.pop('completed')
t['completed'] = datetime.datetime.now()
print(t['completed'])  # datetime