Requires adding solution.py

Author: laike9m

README.md

@@ -30,7 +30,7 @@ flask --app app run --debug
 
 You're more than welcome to contribute new challenges!
 
-All challenges live under the [`challenges/`](https://github.com/laike9m/Python-Type-Challenges/tree/main/challenges) directory, and it's pretty easy to add a new one: **you only need to create a new folder, add a `question.py`, and that's it**. See [here](docs/Contribute.md) for a detailed guidance.
+All challenges live under the [`challenges/`](https://github.com/laike9m/Python-Type-Challenges/tree/main/challenges) directory, and it's pretty easy to add a new one: **you only need to create a new folder, add a `question.py` and a `solution.py`, and that's it**. See [here](docs/Contribute.md) for a detailed guidance.
 
 ## Got Questions?
 

docs/Contribute.md

@@ -8,7 +8,7 @@
 
    For example, say you want to add a new challenge about [Protocols](https://mypy.readthedocs.io/en/stable/protocols.html). Since this is an advanced topic, you may name the directory `advanced-protocol`.
 
-4. Put a `question.py` in the new directory. Here's an example:
+4. Put a `question.py` and a `solution.py` in the new directory. Here's an example:
    ```python
    """
    TODO:
@@ -53,6 +53,24 @@
        foo({"foo": 1})
    ```
 
+   And the `solution.py` shall look like the same as `question.py`, except that it has a solution provided.
+
+   ```python
+   """
+   TODO:
+
+   foo should accept a dict argument, both keys and values are string.
+   """
+
+   def foo(x: dict[str, str]): pass
+
+   def should_pass():
+       foo({"foo": "bar"})
+
+   def should_fail():
+       foo({"foo": 1})
+   ```
+
 5. Test with [`mypy`](https://mypy.readthedocs.io/) to make sure your new challenge works as expected.
 
 6. Create a Pull Request.