Interfaces working?

example/src/main.nub

@@ -1,27 +1,32 @@
+extern func puts(fmt: cstring)
+
 interface Printable
 {
     func print()
 }
 
-struct Human : Printable {
+struct Human : Printable
+{
     name: cstring
 
-    func print_name()
-    {
-        puts(this^.name)
-    }
-
     func print()
     {
-        puts("example")
+        puts(this^.name)
     }
 }
 
 func main(args: []cstring): i64
 {
-    let human: Human = alloc Human {
+    let human = alloc Human {
         name = "oliver"
     }
+
     human.print()
+    print_printable(human)
     return 0
 }
+
+func print_printable(printable: Printable)
+{
+    printable.print()
+}