icalendar rrule only accept a dict, but dateutil.rrules are not dicts.

[the-moog]

Suggest adding a helper function or make the rrule parameter also accept a str so that you can use

cal.add("rrule", rr)
#or
cal.add(''rrule", str(rr))

e.g.
def rrule2dict(rule):
rr = {}
s = str(rule)
s = s.replace("\r", ";")
s = s.replace("\n", ";")
for kv in s.split(";"):
if "=" in kv:
k, v = kv.split("=")
rr[k] = v
elif ":" in kv:
k, v = kv.split(":")
rr[k] = v
else:
raise ValueError
return rr