Genie is a relatively new language similar to Python but compiles to C. Due to its young age it lacks current and complete documentation. Update wiki.gnome.org/Projects/Genie to document defining and calling async methods.
Examples can be found in libsoy and lightmelody source code, but you may still need to do some experimentation to document this correctly and write up a short example. Students who have not completed at least a few Genie tasks will not be allowed to claim this task to avoid overwhelming mentors with help requests.
While working on this task you should join and remain in #CopyleftGames on Freenode to get help, feedback, and guidance from mentors and other developers.