Shows how to implement a SimPy-like simulation using timeouts and generators.

blinker.py

from collections import defaultdict

def blinker(env):
    while True:
        print 'Blink at {}!'.format(env.now)
        yield 5

class BlinkerEnvironment(object):

    def __init__(self, blinkers=4):
        self.now = 0
        self.blinkers = defaultdict(list)
        for idx in xrange(blinkers):
            # blinkers are scheduled by what they yield.
            self.blinkers[idx].append(blinker(self))

    def run(self, until=100):
        while self.now < until:
            if self.now in self.blinkers:
                for blinker in self.blinkers.pop(self.now):
                    timeout = blinker.next() + self.now
                    self.blinkers[timeout].append(blinker) 
            self.now = min(self.blinkers.keys())

if __name__ == "__main__":
    env = BlinkerEnvironment()
    env.run()