pratchett describes the assassins' guild in "the art of discworld" as a typical british public school with the knobs turned up to eleven. like a british public school, it is divided into houses, often named for a deadly animal. the most oft-mentioned is viper house, though scorpion, tree frog, raven and cobra houses have also been mentioned. initially a purely male institution, it has recognised female students as being at least equal to their brothers in the matter of inventive killing, and has opened black widow and mantis houses for girls.