Before you can submit any code we need all contributors to sign a contributor license agreement. By signing a contributor license agreement (CLA) you're basically just attesting to the fact that you are the author of the contribution and that you're freely contributing it under the terms of the MIT License.
When you contribute to the rxn4chemistry project with a new pull request, a bot will evaluate whether you have signed the CLA. If required, the bot will comment on the pull request, including a link to accept the agreement. The individual CLA document is available for review in this repo. You can sign the agreement right away by opening an issue clicking here.