How to get a reference of a type from my element attribute to create an import statement?

I am generating code from a function

```
@mycodegen
List getCats() {
return cats;
}
```

I need now to get an import statement when I reproduce the call method when generating code in my library builder, otherwise a reference to ```Cat``` will be missing. I can do this in the generator:

`callMethod.type.returnType.element.location`

which produces something like

`asset:example/test/Cat.dart;asset:example/test/Cat.dart;Cat`

I would then have to do some string manipulation to get the bits I want to create an import statment. Is this best practice or is there an easier way?

Start with the generator entry point shown in the issue and trace callMethod.type.returnType.element.location for the Cat type. Determine whether source_gen exposes a supported way to obtain the needed import reference without string manipulation, and document the recommended approach and what generated output should contain.

Written by the indexing model from the issue text.