AnimalProtocol protocol requires two type methods:
printAChild. As explained with the type property requirements, we can only use the
static keyword to specify a type method requirement, but we can use either
class when we implement the type method in the class that conforms to the protocol. The usage of the
static keyword doesn't have the same meaning that this keyword has when we use it in classes; that is, we can still declare type methods that can be overridden in the classes that conform to the protocol by declaring them with the
class keyword in the respective classes. The following line shows the type method requirement for
static func printALeg()
The protocol defines ...