An example of using a custom type as a type constraint in Go generics.
With Go support for generics, we no longer need to declare interface{} as a type for passing a value to a function. We can now use type parameter and type constraint to define the set of types the generic function or type would accept.
In this example, we "constrain" the parameter type T to the interface Animal. So any types that implement the behaviors ie. Talk and Species functions can be passed to the generic function Print which accepts the type Animal.