DateTime parser implementation does not know about several of the important
daylight saving time zone variants in US. 

   >>> hard_time = 'Fri, 13 Mar 2009 10:30:00 EDT'
   >>> easy_time = 'Fri, 13 Mar 2009 10:30:00 EST'
   >>> from DateTime import DateTime
   >>> some_time = DateTime(easy_time)

A call to ``bad_time = DateTime(hard_time)`` throws an Exception in
older zope versions.  In Plone 4 it is no longer thrown, so the
underlying Zope has probably been brought up-to-date.  At this point,
extendeddatetime is relegated to helping to maintain functionality in
older Zope versions.  For the record, this is the error that was
thrown::

   Traceback (most recent call last):
       ...
   SyntaxError: Fri, 13 Mar 2009 10:30:00 EDT

Although it would be nice to fix DateTime, that's going to take a while, 
and this is one of those areas where due to the many "dodgy" RSS formats 
out there, we will always need a workaround to something, so let's get on 
and test our wrapper! 

   >>> from Products.feedfeeder.extendeddatetime import extendedDateTime
   >>> good_time = extendedDateTime(hard_time)
   >>> print good_time
   2009/03/13 10:30:00 GMT-4
   
Nice.

In some feeds no primary time standard is especified, add and DateTime throws an error when zope unpickels it. We add GMT.

   >>> a_time = 'Thu, 09 Jan 2014 09:19:20 +0000'
   >>> from Products.feedfeeder.extendeddatetime import extendedDateTime
   >>> better_time = extendedDateTime(a_time)
   >>> print better_time
   2014/01/09 09:19:20 GMT+0

