reorganize: interfaces section

interfaces/03-nonstructs/main.go

@@ -0,0 +1,27 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+func main() {
+	var (
+		// mobydick  = book{title: "moby dick", price: 10}
+		minecraft = game{title: "minecraft", price: 20}
+		tetris    = game{title: "tetris", price: 5}
+	)
+
+	var items []game
+	items = append(items, minecraft, tetris)
+
+	// you can attach methods to a compatible type on the fly:
+	my := list([]game{minecraft, tetris})
+
+	// you can call methods even on a nil value
+	// my = nil
+
+	my.print() // or: list.print(items)
+}