Hi Sarah,

here's updated patch with your tips.

David, the way I test new packages is either by running:
[1]
guix shell --check --pure -D guix

or 
[2]
guix build -L <load_path>


[1] https://guix.gnu.org/manual/en/html_node/Invoking-guix-environment.html
[2] https://guix.gnu.org/manual/en/html_node/Common-Build-Options.html

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Petr