Handle functions with *args and **kwargs

[jackmpcollins]

Handle functions with *args and **kwargs by serializing these as normal params (list/array for args, dict/object for kwargs), and using the function signature to parse these correctly into the FunctionCall when returned by the LLM.

Fixes #102

[jackmpcollins]

It takes a little bit of convincing but this appears to work as expected.

from magentic import prompt_chain


def do_something(x: str, y: str, **kwargs: int) -> str:
    print(x)
    print(y)
    print(kwargs)
    return f"you provided {x=}, {y=}, and {kwargs=}!"


@prompt_chain(
    "Call the do_something function passing 'hello' and 'world' for x and y, and also additional kwargs {{a: 1 b: 2 c:3}}",
    functions=[do_something],
)
def chain() -> str:
   ...


out = chain()
print("---")
print(out)

output:

hello
world
{'a': 1, 'b': 2, 'c': 3}
---
The function `do_something` has been called with the arguments x='hello', y='world', and kwargs={'a': 1, 'b': 2, 'c': 3} successfully.