Hi there!
tl;dr: I want to merge https://github.com/collective/icalendar/pull/299
Full story:
I'm maintaining an application (not related to Plone) that uses this library. During fixing one bug, I found that icalendar can read from string event with any rrule because of using text as a default type (great!), but... failed when try to save it to string because saving method doesn't have default type.
Based on rule described in docstring https:// github .com/collective/icalendar/blob/master/src/icalendar/prop.py#L33 when it's possible to read, it should be also possible to save to string. So I made a PR that add this 
Unfortunately, there is no one active on Github who can review this change. Could anyone help?