update: powerdrawer interface

interfaces/04-interfaces/power/mixer.go

@@ -0,0 +1,20 @@
+// 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
+
+import (
+	"fmt"
+)
+
+// Mixer can be powered
+type Mixer struct{}
+
+// Draw power to a Mixer
+func (Mixer) Draw(power int) {
+	fmt.Printf("Mixer is drawing %dkW of electrical power.\n", power)
+}