1 """Deal with various biological databases and services on the web. 2 """ 3 import time 4 5 -class RequestLimiter: 6 # This class implements a simple countdown timer for delaying WWW 7 # requests. 8 - def __init__(self, delay): 9 self.last_time = 0.0 10 self.delay = delay 11 - def wait(self, delay=None): 12 if delay is None: 13 delay = self.delay 14 how_long = self.last_time + delay - time.time() 15 if how_long > 0: 16 time.sleep(how_long) 17 self.last_time = time.time() 18