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# Simple version:

import sys, time

class RetryError(Exception):
   
pass

def retryloop(attempts, timeout):
    starttime
= time.time()
    success
= set()
   
for i in range(attempts):
        success
.add(True)
       
yield success.clear
       
if success:
           
return
       
if starttime + timeout < time.time():
           
break
   
raise RetryError

"""
Usage:

for retry in retryloop(10, timeout=30):
    try:
        something
    except SomeException:
        retry()

for retry in retryloop(10, timeout=30):
    something
    if somecondition:
        retry()

"""


# Fancy version:

def fancyretryloop(attempts, timeout=None, delay=0, backoff=1):
    starttime
= time.time()
    success
= set()
   
for i in range(attempts):
        success
.add(True)
       
yield success.clear
       
if success:
           
return
        duration
= time.time() - starttime
       
if timeout is not None and duration > timeout:
           
break
       
if delay:
            time
.sleep(delay)
            delay
= delay * backoff

    e
= sys.exc_info()[1]

   
# No pending exception? Make one
   
if e is None:
       
try: raise RetryError
       
except RetryError as e: pass

   
# Decorate exception with retry information:
    e
.args = e.args + ("on attempt {0} of {1} after {2:.3f} seconds".format(i, attempts + 1, duration),)

   
raise

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