python3-dateutil 2.4.2-1 (amd64 binary) in ubuntu xenial

 It features:
 .
  * computing of relative deltas (next month, next year, next monday, last week
    of month, etc);
  * computing of relative deltas between two given date and/or datetime objects
  * computing of dates based on very flexible recurrence rules, using a superset
    of the iCalendar specification. Parsing of RFC strings is supported as well.
  * generic parsing of dates in almost any string format
  * timezone (tzinfo) implementations for tzfile(5) format files
    (/etc/localtime, /usr/share/zoneinfo, etc), TZ environment string (in all
    known formats), iCalendar format files, given ranges (with help from
    relative deltas), local machine timezone, fixed offset timezone, UTC
    timezone
  * computing of Easter Sunday dates for any given year, using Western, Orthodox
    or Julian algorithms