def get_backoff_time(self) -> float:
        """Formula for computing the current backoff

        :rtype: float
        """
        # We want to consider only the last consecutive errors sequence (Ignore redirects).
        consecutive_errors_len = len(
            list(
                takewhile(lambda x: x.redirect_location is None, reversed(self.history))
            )
        )
        if consecutive_errors_len <= 1:
            return 0

        backoff_value = self.backoff_factor * (2 ** (consecutive_errors_len - 1))
        if self.backoff_jitter != 0.0:
            backoff_value += random.random() * self.backoff_jitter
        return float(max(0, min(self.backoff_max, backoff_value)))
Formula for computing the current backoff

        :rtype: float
        
src/urllib3/util/retry.py