Fetch a Bucket for the given key.

        rate and capacity might be overridden from the Throttler defaults.

        Args:
            rate (float): Units regenerated by second, or None to keep
                Throttler defaults
            capacity (int): Maximum units available, or None to keep Throttler
                defaults

def get_bucket(self, key, rate=None, capacity=None, **kwargs):
        """Fetch a Bucket for the given key.

        rate and capacity might be overridden from the Throttler defaults.

        Args:
            rate (float): Units regenerated by second, or None to keep
                Throttler defaults
            capacity (int): Maximum units available, or None to keep Throttler
                defaults
        """
        return buckets.Bucket(
            key=key,
            rate=rate or self.rate,
            capacity=capacity or self.capacity,
            storate=self.storate,
            **kwargs)