# Hello World

Let’s first get used to the infrastructure for writing, running, and debugging recipes.

Create a file `hello.py` anywhere:

{% code title="hello.py" %}

```python
from ice.recipe import recipe


async def say_hello():
    return "Hello world!"


recipe.main(say_hello)
```

{% endcode %}

Run the recipe:

```shell
python hello.py
```

This will run the recipe and save an execution trace.

On the terminal, you will see a trace link and output:

```
Trace: http://localhost:8935/traces/01GE0GN5PPQWYGMT1B4GFPDZ09
Hello world!
```

If you follow the trace link (yours will be different), you will see a function node that you can click on, inspect inputs/outputs for, and show source code for:

<figure><img src="https://393762053-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FFqoUXVrYie7Ht7Fi4JrU%2Fuploads%2FLv9Zk1vEC8Rh3qkNJEb4%2FScreenshot%2068F7bqCl%402x.png?alt=media&#x26;token=3c1f17b5-f9d5-4bec-a0ec-a776f896ff08" alt=""><figcaption><p>Your first execution trace (<a href="https://ice.ought.org/traces/01GE0GN5PPQWYGMT1B4GFPDZ09">view online</a>)</p></figcaption></figure>

<details>

<summary>The recipe, line by line</summary>

* We use `recipe.main` to denote the recipe entry point and to automatically trace all global async functions that were defined in this file. Synchronous functions are assumed to be simple and fast, and not worth tracing.
* `recipe.main` must appear at the bottom of the file.
* The entry point must be async.
* Most recipe functions will be async so that language model calls are parallelized as much as possible.
* Different recipes take different arguments, which will be provided as keyword arguments to the entry point. This recipe doesn’t use any arguments.

</details>

### Exercises

1. Add another function and call it from `say_hello`. Does it show up in the trace? What if you make it async and call it as `result = await my_function()`?