+ """A helper for @retry_predicate that retries a decorated
+ function as long as it keeps returning False.
+
+ >>> import time
+
+ >>> counter = 0
+
+ >>> @retry_if_false(5, delay_sec=1.0, backoff=1.1)
+ ... def foo():
+ ... global counter
+ ... counter += 1
+ ... return counter >= 3
+
+ >>> start = time.time()
+ >>> foo() # fail, delay 1.0, fail, delay 1.1, succeed
+ True
+
+ >>> dur = time.time() - start
+ >>> counter
+ 3
+ >>> dur > 2.0
+ True
+ >>> dur < 2.2
+ True
+
+ """