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CONTRIBUTING.md

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+Contributing to Zeppelin
+=======
+
+## Design Guidelines
+
+These are some global design goals in Zeppelin.
+
+### D0 - Security in Depth
+We strive to provide secure, tested, audited code. To achieve this, we need to match intention with function. Thus, documentation, code clarity and community review and security discussions are fundamental.
+
+### D1 - Simple and Modular
+Simpler code means easier audits, and better understanding of what each component does. We look for small files, small contracts, and small functions. If you can separate a contract into two independent functionalities you probably should do it.
+
+### D2 - Naming Matters
+
+We take our time with picking names. Code is going to be written once, and read hundreds of times. Renaming for clarity is encouraged.
+
+### D3 - Tests
+
+Write a test for all your code. We encourage Test Driven Development so we know when our code is right. 
+
+### D4 - Check preconditions and post-conditions
+TODO
+
+### D5 - Consistency Everywhere
+
+Consistency on the way classes are used is paramount to allow an easier understanding of the library.
+
+## Style Guidelines
+
+The design guidelines have quite a high abstraction level. These style guidelines are more concrete and easier to apply, and also more opinionated.
+
+### General
+
+#### G0 - Default to Solidity's official style guide.
+
+Follow the official Solidity style guide: http://solidity.readthedocs.io/en/latest/style-guide.html
+
+#### G1 - No Magic Constants
+
+Avoid constants in the code as much as possible. Magic strings are also magic constants.
+
+#### G2 - Code that Fails Early
+
+We ask our code to fail as soon as possible when an unexpected input was provided or unexpected state was found.
+
+#### G3 - Internal Amounts Must be Signed Integers and Represent the Smallest Units.
+
+Avoid representation errors by always dealing with weis when handling ether. GUIs can convert to more human-friendly representations. Use Signed Integers (int) to prevent underflow problems.
+
+
+### Testing
+
+#### T1 - Tests Must be Written Elegantly
+
+Style guidelines are not relaxed for tests. Tests are a good way to show how to use the library, and maintaining them is extremely necessary.
+
+Don't write long tests, write helper functions to make them be as short and concise as possible (they should take just a few lines each), and use good variable names.
+
+#### T2 - Tests Must not be Random
+
+Inputs for tests should not be generated randomly. Also, the type and structure of outputs should be checked.
+
+
+### Documentation
+
+TODO
+
+## Pull Request Workflow
+
+Our workflow is based on GitHub's pull requests. We use feature branches, prepended with: `test`, `feature`, `fix`, `refactor`, or `remove` according to the change the branch introduces. Some examples for such branches are:
+```sh
+git checkout -b test/some-module
+git checkout -b feature/some-new-stuff
+git checkout -b fix/some-bug
+git checkout -b remove/some-file
+```
+
+We expect pull requests to be rebased to the master branch before merging:
+```sh
+git remote add zep git@github.com:OpenZeppelin/zep-solidity.git
+git pull --rebase zep master
+```
+
+Note that we require rebasing your branch instead of merging it, for commit readability reasons.
+
+After that, you can push the changes to your fork, by doing:
+```sh
+git push origin your_branch_name
+git push origin feature/some-new-stuff
+git push origin fix/some-bug
+```
+
+Finally go to [github.com/OpenZeppelin/zep-solidity](https://github.com/OpenZeppelin/zep-solidity) in your web browser and issue a new pull request.
+
+Main contributors will review your code and possibly ask for changes before your code is pulled in to the main repository.  We'll check that all tests pass, review the coding style, and check for general code correctness. If everything is OK, we'll merge your pull request and your code will be part of Zeppelin.
+
+If you have any questions feel free to post them to
+[github.com/OpenZeppelin/zep-solidity/issues](https://github.com/OpenZeppelin/zep-solidity/issues).
+
+Thanks for your time and code!