Function realObjectType

Determine the type of an z.isRealObject: an 'instance' of a class or a plain 'pojso' object.

If it is not an z.isRealObject, it returns undefined, which means you need to z.type() it to get the proper type.

https://stackoverflow.com/questions/30758961/how-to-check-if-a-variable-is-an-es6-class-declaration/69316645#69316645