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pull_request_template.md

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+Thank you for your contribution to the PynPoint repo! Before submitting this PR, please make sure:
+
+- [ ] To read the documentation page on the [Python guidelines](https://pynpoint.readthedocs.io/en/latest/python.html).
+- [ ] That your branch is up to date with the master branch of the upstream PynPoint repo.
+- [ ] To run both `pycodestyle` and `pylint` on the code that has been added or changed.
+- [ ] That the documentation is succesfully build by running `make docs` in your local repo folder.
+- [ ] That all unit tests are finishing after running `make test` in your local repo folder.
+- [ ] To add unit tests in case there are new pipeline modules and/or functionalities added.