I recently added this to snakemake master
You can view, comment on, or merge this pull request online at:

  https://github.com/kyleam/snakemake-mode/pull/5

-- Commit Summary --

  * Add shadow keyword for rules

-- File Changes --

    M snakemake-mode.el (2)

-- Patch Links --

https://github.com/kyleam/snakemake-mode/pull/5.patch
https://github.com/kyleam/snakemake-mode/pull/5.diff

---
Reply to this email directly or view it on GitHub:
https://github.com/kyleam/snakemake-mode/pull/5