Naming `class_getattr` is an historical mistake since it takes an object, not a type, as first argument. Not having a primitive to execute a lookup *directly* on a type has become a problem in #2. We should implement a `mro_lookup` primitive. Doing `class_getattr` could then be written as `mro_lookup(type(x), "__method__")`. This is both more expressive and more accurately named.