Capture entire json as single variable in guidance

[alexmadey-oc]

@guidance
def character_maker(lm, id, description, valid_weapons):
    lm += f"""\
    The following is a character profile for an RPG game in JSON format.
    ```json
    {{
        "id": "{id}",
        "description": "{description}",
        "name": "{gen('name', stop='"')}",
        "age": {gen('age', regex='[0-9]+', stop=',')},
        "armor": "{select(options=['leather', 'chainmail', 'plate'], name='armor')}",
        "weapon": "{select(options=valid_weapons, name='weapon')}",
        "class": "{gen('class', stop='"')}",
        "mantra": "{gen('mantra', stop='"')}",
        "strength": {gen('strength', regex='[0-9]+', stop=',')},
        "items": ["{gen('item', list_append=True, stop='"')}", "{gen('item', list_append=True, stop='"')}", "{gen('item', list_append=True, stop='"')}"]
    }}```"""
    return lm

I'm working on something very similar to the example above. Instead of capturing the individual fields, e.g. "name" or "age", I want to capture the entire json as a single variable so I can parse it. I've tried moving the part that generates only the json I want to capture into another stateful guidance function and using the capture function, but this doesn't work. It looks like

lm += capture(gen_character_json(), "character_json")

I get an error AttributeError: 'StatefulFunction' object has no attribute 'nullable'. On the other hand, this seems to work if the guidance function is stateless, but this case requires stateful. How can I capture the full json?