How to use wait

Revision:
0:7780c906c1c7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Thu Jan 19 11:34:26 2017 -0600
@@ -0,0 +1,12 @@
+#include "mbed.h"
+
+DigitalOut heartbeat(LED1);
+
+int main() {
+    while (1) {
+        heartbeat = 1;
+        wait(0.5);
+        heartbeat = 0;
+        wait(0.5);
+    }
+}