diff --git a/Functions.md b/Functions.md
index 99cdd34..9476782 100644
--- a/Functions.md
+++ b/Functions.md
@@ -19,6 +19,9 @@ function main(args) {
 }
 
 exports.main = main;
+
+// You must explicitly specify where to find the function.
+AsyncFunction._filename = "program.js";
 ```
 
 #### In the console
@@ -50,6 +53,9 @@ function main(args) {
 exports.main = main;
 exports.onShoutcut = onShoutcut;
 exports.sub_01 = sub_01;
+
+// You must explicitly specify where to find the function.
+AsyncFunction._filename = "program.js";
 ```
 
 ## GeneratorFunction