Pydantic works with [mypy](http://mypy-lang.org/) provided you use the annotation-only version of
required fields:

```py
{!.tmp_examples/mypy.py!}
```
_(This script is complete, it should run "as is")_

You can also run it through mypy with:

```bash
mypy \
  --ignore-missing-imports \
  --follow-imports=skip \
  --strict-optional \
  pydantic_mypy_test.py
```

## Strict Optional

For your code to pass with `--strict-optional`, you need to to use `Optional[]` or an alias of `Optional[]`
for all fields with `None` as the default. (This is standard with mypy.)

Pydantic provides a few useful optional or union types:

* `NoneStr` aka. `Optional[str]`
* `NoneBytes` aka. `Optional[bytes]`
* `StrBytes` aka. `Union[str, bytes]`
* `NoneStrBytes` aka. `Optional[StrBytes]`

If these aren't sufficient you can of course define your own.