Companion

Answer a new object instance of this descriptor based on the set of objects that will be considered instances of that type. Normalize the cases where the set has zero or one elements to use BottomTypeDescriptor and InstanceTypeDescriptor, respectively.

Answer a new object instance of this descriptor based on the single object that will be considered an instance of that type. If a type is specified, all subtypes will also be considered instances of that type.

The CheckedMethod for instanceTypeOrMetaOn.