Can part directives be improved

In order to create part files in dart, we need to write part directives in all the part files like this

**1. Base file**
```dart
part 'my_file.g.dart'
```
And in the part file
```dart
part of 'my_file.dart'
```

I think in augmentation library, we also need to write augmentation directives in all the files.

My question is if we can implement **part** or **augmentation** by writing related directives in only one file, either of both. Like when I already told the compiler that the base file has a part file named `'my_file.g.dart'`, then why i need to tell the compile again that the part file is of the file named `'my_file.dart'` and vice versa. This seems ridiculous.

Suppose we don't need to write **part of** directive in the part file, we can define a part file in multiple base files. On the other side if we can omit **part** directive in _base file_. All we need to do is to write **part of** directive in the part file. This looks good.

This can be tried in **augmentation library** also.

Start with the issue's examples of Dart part and augmentation directives, then review the language-design discussion in this repository. Compare the proposed one-sided directive forms and consider how they affect ownership and ambiguity. Done means reaching and documenting a language-design decision, not merely changing one file.

Written by the indexing model from the issue text.