*********** My least favorite animal is $ leastFavoriteAnimal $.
*********** (set in another template, leastFavoriteAnimal.st)
*********** Notice that this template file uses CamelCase rather than dashes to separate words.
Otherwise there's an error with included templates.
So, in general: avoid template file names with dashes or underscores, and just use CamelCase for templates.
Numbers are also not allowed.
Try uncommenting the next line and see what you get:
$!
Include least-favorite-animal.st: $ least-favorite-animal.st $ !$