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1. Read [instructions for contributors](https://catboost.ai/docs/concepts/development-and-contributions.html).
2. Make sure [the code builds](https://catboost.ai/en/docs/concepts/build-from-source).
3. If you add new functionality [add tests](https://catboost.ai/en/docs/concepts/development-and-contributions#run-tests) to check it.
4. [Run existing tests](https://catboost.ai/en/docs/concepts/development-and-contributions#run-tests) to make sure you haven't broken anything.
5. If you haven't already, sign [the Contributor License Agreement](https://yandex.ru/legal/cla/).