```
Welcome to Kotlin version 1.2.41 (JRE 1.8.0_17...
# announcementsj
jmccance
06/06/2018, 9:50 PM Copy code
Welcome to Kotlin version 1.2.41 (JRE 1.8.0_172-b01)
Type :help for help, :quit for quit
>>> enum class Animal { CAT, DOG }
>>> operator fun Animal.inc(): Animal = <http://Animal.CAT|Animal.CAT>
error: 'operator' modifier is inapplicable on this function: receiver must be a supertype of the return type
operator fun Animal.inc(): Animal = <http://Animal.CAT|Animal.CAT>
^8 Views