[Zope] Manipulating Dates in Zope

Is there a way in Zope (preferably in a python script rather than DTML) to manipulate dates so that you can calculate the date, say, six months ahead (regardless of the intermediate months having 28/29/30/31 days)? Some dates must be calculated on increments other than days. For example, a response to something may be due three months from the present date (e.g., February 4, 2002) or five years from the present date (e.g., December 4, 2006). Simply adding days would not take into account months that have more/less than 30 days. Does Zope/python have any tools that can be employed for the above in a python script? Thanks in advance, Ron