'Gets the current retry timings (if any) for a given destination.
Args:
destination (str)
Returns:
None if not retrying
Otherwise a dict for the retry scheme'

@cached(max_entries=10000)
def get_destination_retry_timings(self, destination):

    return self.runInteraction('get_destination_retry_timings', self._get_destination_retry_timings, destination)
