Check if the function is declared before declaring it.

Author: NikoGrano

composer.json

@@ -11,7 +11,7 @@
         }
     ],
     "autoload": {
-        "files": [ "src/functions.php" ]
+        "files": [ "src/functions_include.php" ]
     },
     "require": {
     	"php": ">=5.3",

src/functions_include.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Clue\React\Block;
+
+if (!function_exists('Clue\\React\\Block\\sleep')) {
+    require __DIR__ . '/functions.php';
+}
+