From 1ffc847737ae2e72578c8875b5dac2d364fcf41f Mon Sep 17 00:00:00 2001
From: Carlos <carlos.fenollosa@gmail.com>
Date: Wed, 1 Apr 2015 09:45:59 +0200
Subject: [PATCH] missing file for lesson 21

---
 21-shell/libc/function.h | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 21-shell/libc/function.h

diff --git a/21-shell/libc/function.h b/21-shell/libc/function.h
new file mode 100644
index 0000000..bf656ed
--- /dev/null
+++ b/21-shell/libc/function.h
@@ -0,0 +1,8 @@
+#ifndef FUNCTION_H
+#define FUNCTION_H
+
+/* Sometimes we want to keep parameters to a function for later use
+ * and this is a solution to avoid the 'unused parameter' compiler warning */
+#define UNUSED(x) (void)(x)
+
+#endif