In the docs, specify when a method can also return nil (besides its usual types)
In the docs, specify when a method can also return nil (besides its usual types)

nicolasmccurdy/magician-lisp,nicolasmccurdy/magician-haskell,nicolasmccurdy/magician-clojure,nicolasmccurdy/magician-clojure,nicolasmccurdy/magician,nicolasmccurdy/magician-lisp