What's Changed
Utils
* Added `getFirstBlockForL1Block` and `getBlockRangesForL1Block` for looking up L2 and Orbit blocks by bartlomiej94 in https://github.com/OffchainLabs/arbitrum-sdk/pull/317
Erc20Bridger
* Enabled specifying `toAddress` in `getL2WithdrawalEvents` by spsjvc in https://github.com/OffchainLabs/arbitrum-sdk/pull/324
**Full Changelog**: https://github.com/OffchainLabs/arbitrum-sdk/compare/v3.1.7...v3.1.8