Python timed scheduler - scheduling

Question

Okay, so I'm working on a scheduler and I was thinking of something like, timeOut(3,print,'hello') and it would print hello every three seconds, I have tried some methods but all failed. Also Using time.sleep for this wouldn't quite work because I need to run other tasks as well besides just one
Edit:
I found out how to do what I needed, sorry for being confusing but this did the trick for what I needed, thanks for answering everyone.
class test:
def __init__(self):
self.objectives = set()
class Objective:
pass
def interval(self,timeout,function,*data):
newObjective = self.Objective()
newObjective.Class = self
newObjective.timeout = time.time()+timeout
newObjective.timer = timeout
newObjective.function = function
newObjective.repeate = True
newObjective.data = data
self.objectives.add(newObjective)
return True
def runObjectives(self):
timeNow = time.time()
for objective in self.objectives:
timeout = objective.timer
if objective.timeout <= timeNow:
objective.function(*objective.data)
if objective.repeate:
objective.timeout = timeNow + timeout
self.main()
else:
self.objectives.remove(objective)
print('removed')
def main(self):
while True:
self.runObjectives()

Answer 1

The standard library includes a module called sched for scheduling. It can be adapted to work in a variety of environments using the delayfunc constructor parameter. Using it your question would likely read:
def event():
scheduler.enter(3, 0, event, ()) # reschedule
print('hello')
Now it depends on how you run the other tasks. Are you using an event loop? It probably has a similar scheduling mechanism (at least twisted has callLater and GObject has timeout_add). If all else fails, you can spawn a new thread and execute a sched.scheduler with time.sleep there.