Python: Fix SKFunction.invoke_stream_async

[johnliu55-msft]

Motivation and Context

The invoke_stream_async method on a native SKFunction is not functional. The following sample code should work:

import asyncio

import semantic_kernel as sk
from semantic_kernel.skill_definition import sk_function


class StreamNativeSkill:
    @sk_function(name="stream")
    async def stream(self, input: str) -> None: # This should also work: -> AsyncGenerator
        for i in range(5):
            await asyncio.sleep(1)
            yield input + str(i)


async def main():
    kernel = sk.Kernel()

    skill = kernel.import_skill(StreamNativeSkill(), "stream_skill")
    native_stream_func = skill["stream"]

    async for chunk in native_stream_func.invoke_stream_async("HELLO!"):
        print(chunk)


if __name__ == "__main__":
    asyncio.run(main())

And should output:

HELLO!0
HELLO!1
HELLO!2
HELLO!3
HELLO!4

But now it only shows:

HELLO!

Description

Add four new DelegateTypes for native asynchronous generator functions for different types of parameters:

• OutAsyncGenerator: No parameter, has yield
• InStringOutAsyncGenerator: One str parameter, has yield
• InContextOutAsyncGenerator: One SKContext parameter, has yield
• InStringAndContextOutAsyncGenerator: Both str and SKContext parameters, has yield

Along with these four new types, add four new DelegateInference functions to detect the types:

• infer_out_async_generator
• infer_in_string_out_async_generator
• infer_in_context_out_async_generator
• infer_in_string_and_context_out_async_generator

And because the async generator functions needs to use inspect.isasyncgenfunction function to check instead of inspect.iscoroutinefunction, add another parameter is_asyncgenfunc to all the infer functions.

And finally, fix SKFunction._invoke_native_stream_async so that it can correctly iterating from an async generator function.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[alexchaomander]

This looks good to me! Thank you for adding this!