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+# Contributing to this repository
+
+## Getting started
+
+Before you begin:
+
+- Have you read the [code of conduct](./CODE_OF_CONDUCT.md)?
+
+## Reviewing
+
+We often use **must**, _should_, or may as a leveling label of comments.
+
+**must**
+
+What reviewer think you must fix. For example
+
+![must The unit of responseTimeout is milliseconds rather than seconds.](https://user-images.githubusercontent.com/546312/127770085-fec9053b-1291-4728-854e-0ccf7c3f44d5.png)
+
+_should_
+
+What reviewer think you should fix or want reasonable explanations. For example
+
+![should Why do you choose 7 days for that? I think it's too long for response timeout and maybe 24 hours is enough.](https://user-images.githubusercontent.com/546312/127770162-bdd5b421-bde4-446c-82cb-01aa7ec3504a.png)
+
+may
+
+What reviewer feel not good or strange. It's more like advice and you can
+ignore. For example
+
+![may I feel responseTimeoutSeconds is a bit better than responseTimeout because it tells the unit of the value.](https://user-images.githubusercontent.com/546312/127770316-996b5b62-7aba-48b6-b558-3b4fa30f1c1b.png)