Stitcher is a very young open source project, but you're always welcome to make contributions.
When submitting a contribution, you should always create a pull request with the develop branch.
Furthermore you should also search for and mention related issues your pull request targets.
Writing unit tests is highly recommended. Following PSR-2 guidelines is required. Note that some code in this repository is not PSR-2 compliant yet. You're always free to make the necessary changes to match PSR-2.