iface: improved example

iface/01-iface.go

@@ -1,11 +0,0 @@
-package main
-
-type Strummer interface {
-	Strum()
-}
-
-type Bocchi struct {
-	Guitar string
-}
-
-var _ Strummer = (*Bocchi)(nil)

iface/chord.go

@@ -0,0 +1,3 @@
+package main
+
+type Chord string

iface/guitarist.go

@@ -0,0 +1,13 @@
+package main
+
+type Guitarist interface {
+	Strum(chord Chord)
+}
+
+type Bocchi struct {
+	Guitar string
+}
+
+func (b *Bocchi) Strum(chord string) {}
+
+var _ Guitarist = (*Bocchi)(nil)