improve logging

lexer.go

@@ -103,7 +103,7 @@ func (l *Lexer) acceptRun(valid string) {
 
 func (l *Lexer) emit(t ItemType) {
 	i := Item{t, l.input[l.start:l.pos]}
-	log.Printf("emitting Item: %#+v\n", i)
+	log.Printf("emitting Item: %s\n", i.String())
 	l.items <- i
 	l.start = l.pos
 }