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CONTRIBUTING.md

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+# Contributing
+
+Contributions of all kinds are welcome. In particular pull requests are appreciated. 
+The authors will endeavour to help walk you through any issues in the pull request
+discussion, so please feel free to open a pull request even if you are new to such things.
+
+## Issues
+
+The easiest contribution to make is to [file an issue](https://github.com/lmcinnes/umap/issues/new).
+It is beneficial if you check the [FAQ](https://umap-learn.readthedocs.io/en/latest/faq.html), 
+and do a cursory search of [existing issues](https://github.com/lmcinnes/umap/issues?utf8=%E2%9C%93&q=is%3Aissue).
+It is also helpful, but not necessary, if you can provide clear instruction for 
+how to reproduce a problem. If you have resolved an issue yourself please consider
+contributing to the FAQ to add your problem, and its resolution, so others can
+benefit from your work.
+
+## Documentation
+
+Contributing to documentation is the easiest way to get started. Providing simple
+clear or helpful documentation for new users is critical. Anything that *you* as 
+a new user found hard to understand, or difficult to work out, are excellent places
+to begin. Contributions to more detailed and descriptive error messages is
+especially appreciated. To contribute to the documentation please 
+[fork the project](https://github.com/lmcinnes/umap/issues#fork-destination-box)
+into your own repository, make changes there, and then submit a pull request.
+
+## Code
+
+Code contributions are always welcome, from simple bug fixes, to new features. To
+contribute code please 
+[fork the project](https://github.com/lmcinnes/umap/issues#fork-destination-box)
+into your own repository, make changes there, and then submit a pull request. If
+you are fixing a known issue please add the issue number to the PR message. If you
+are fixing a new issue feel free to file an issue and then reference it in the PR.
+You can [browse open issues](https://github.com/lmcinnes/umap/issues), 
+or consult the [project roadmap](https://github.com/lmcinnes/umap/issues/15), for potential code
+contributions. Fixes for issues tagged with 'help wanted' are especially appreciated.