```\ndef _debt_interest_since_last_update(_debt_token: address) -> uint256:\n\n    return (\n\n        (block.timestamp - self.last_debt_update[_debt_token])* self._current_interest_per_second(_debt_token)\n        * self.total_debt_amount[_debt_token]\n        / PERCENTAGE_BASE \n        / PRECISION\n    )\n```\n