From 5827eebde3a9d4f5dddf77c516eac39560f57ff6 Mon Sep 17 00:00:00 2001
From: Michael Uleysky <uleysky@poi.dvo.ru>
Date: Tue, 20 Sep 2016 22:24:01 +1000
Subject: [PATCH] Add header guard in builtin.h.

---
 include/builtin.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/builtin.h b/include/builtin.h
index 57165c9..157c7a7 100644
--- a/include/builtin.h
+++ b/include/builtin.h
@@ -1,3 +1,5 @@
+#ifndef BUILTIN_H
+#define BUILTIN_H
 #include <cmath>
 #include "object.h"
 
@@ -114,3 +116,4 @@ const ObjectBase* Arifm1(const ObjectList* input)
 
  return new ObjectError("Arifmetic unary operator","unknown error"); // Impossible case
 }
+#endif