Interfaces are an advanced Go feature, which means that you might not want to use them in your programs if you are not feeling very comfortable with Go. However, interfaces can be very practical when developing big Go programs, which is the main reason for talking about interfaces in this book.
But first, I will talk about methods, which are functions with a special receiver argument. You declare methods as ordinary functions with an additional parameter that appears just before the function name. This particular parameter connects the function to the type of that extra parameter. As a result, that parameter is called the receiver of the method. You will see such functions in a while.
Put simply, interfaces are abstract types that define a set of functions that need to be implemented so that a type can be considered an instance of the interface. When this happens, we...
