The dateutil module provides powerful extensions to the standard
datetime module available in Python. Features include:

* 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, and Windows registry-based time zones;
* Internal up-to-date world timezone information based on Olson's
database;
* Computing of Easter Sunday dates for any given year, using Western,
Orthodox or Julian algorithms;
* More than 400 test cases.