in pyqldb/util/retry.py [0:0]
def calculate_backoff(retry_config, retry_attempt, error, transaction_id):
if retry_config.custom_backoff:
delay = retry_config.custom_backoff(retry_attempt, error, transaction_id)
if delay < 0:
delay = 0
else:
delay = Retry._get_delay_with_equal_jitter(retry_attempt, retry_config)
return delay