Render GitHub source (with line-range) as code-block

Does anyone know of a method of rendering a range of GitHub source as a code-block?

I found a plugin that will render a gist, but not an arbitrary code blob with a line range.

In my imagination, you would write some markdown like:

```cs ```

and it would be rendered on the site as if the code-block was written in the markdown source.

My guess is someone has already done this any my search skills are poor.