tags.get() fails with ValueError: time data '3' does not match format '%Y-%m-%d %H:%M:%S'

[skome]

import pinboard
pb=pinboard.Pinboard(APIKEY)
pb.tags.get() 
/usr/lib/python3.7/_strptime.py in _strptime(data_string, format)
    357     if not found:
    358         raise ValueError("time data %r does not match format %r" %
--> 359                          (data_string, format))
    360     if len(data_string) != found.end():
    361         raise ValueError("unconverted data remains: %s" %
ValueError: time data '3' does not match format '%Y-%m-%d %H:%M:%S'