update

docs/implementation.md

@@ -338,6 +338,7 @@ node test/scenario3_julia_to_julia.js
 **Why the Difference?**
 - Julia supports function overloading and keyword arguments, allowing `NATS_connection` to be passed as an optional parameter
 - JavaScript/Python use a simpler `is_publish` option to control automatic publishing
+- `is_publish` is simply a switch: when `true`, publish automatically; when `false`, return `(env, env_json_str)` without publishing
 - For connection reuse in JavaScript/Python, create a NATS client once and reuse it in your custom `fileserver_upload_handler` or custom publish logic
 
 ## Usage