At first I run
```
flutter create --template=package hello
```

then add dependency `plugin_platform_interface` (https://pub.dev/packages/plugin_platform_interface)
that prevent `implement` for platform-side classes

```
flutter pub add plugin_platform_interface
```

> Extending a platform interface ensures that subclasses will get the default implementations
> from the base class, while platform implementations that implements their platform interface
> will be broken by newly added methods.