Mutate (and likely steps too) code isn't shown in Hamilton UI

# Current behavior
Running mutate decorator (and likely step/pipe) with the Hamilton Tracker shows the correct DAG structure, but no code is attached.

## Screenshots

## Steps to replicate behavior
```python
from hamilton.function_modifiers import mutate
import pandas as pd

def transformed_data(raw_data: pd.DataFrame) -> pd.DataFrame:
return ... # do your regular stuff here

# turns initial_data into initial_data + 1
@mutate(transformed_data)
def _normalize_columns(df: pd.DataFrame) -> pd.DataFrame:
for column in df.columns:
df[column] = (df[column]-df[column].min())/(df[column].max() - df[column].min())
return df

@mutate(transformed_data, outlier_threshold=10)
def _remove_outliers(df: pd.DataFrame, outlier_threshold: float) -> pd.DataFrame:
return df[df < outlier_threshold]
```
driver:
```python
from hamilton_sdk import adapters
from hamilton import driver

tracker = adapters.HamiltonTracker(
project_id=..., # modify this as needed
username="...",
dag_name="mutate_example",
tags={"environment": "DEV", "team": "MY_TEAM", "version": "mutate"},

)
dr = (
driver.Builder()
.with_config({})
.with_modules(mutate_example)
.with_adapters(tracker)
.build()
)
```
## Library & System Information
Latest python, SDK, & hamilton UI versions

# Expected behavior
That the code shows up.

# Additional context
Guess - we're not attaching the source code appropriately or referencing it correctly for the UI to show it.