!python --version

Python 3.12.4

from constants import OPENAI_API_KEY

!pip show langchain-openai | grep "Version:"

Version: 0.2.9

import os

os.environ["OPENAI_API_KEY"] = OPENAI_API_KEY

# https://python.langchain.com/docs/how_to/functions/

from langchain_openai import ChatOpenAI

model = ChatOpenAI(model="gpt-4o-mini")

from langchain_core.runnables import RunnableLambda
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser

from typing import Iterator, List

prompt = ChatPromptTemplate.from_template(
    "Write a comma-separated list of 5 animals similar to: {animal}. Do not include numbers"
)

str_chain = prompt | model | StrOutputParser()

for chunk in str_chain.stream({"animal": "bear"}):
    print(chunk, end="", flush=True)

wolf, lynx, cougar, bison, moose

from typing import AsyncIterator


async def asplit_into_list(
    input: AsyncIterator[str],
) -> AsyncIterator[List[str]]:  # async def
    buffer = ""
    async for (
        chunk
    ) in input:  # `input` is a `async_generator` object, so use `async for`
        buffer += chunk
        while "," in buffer:
            comma_index = buffer.index(",")
            yield [buffer[:comma_index].strip()]
            buffer = buffer[comma_index + 1 :]
    yield [buffer.strip()]

list_chain = str_chain | asplit_into_list

async for chunk in list_chain.astream({"animal": "bear"}):
    print(chunk, flush=True)

['wolf']
['lynx']
['cougar']
['bobcat']
['wolverine']

await list_chain.ainvoke({"animal": "bear"})

['wolf', 'lion', 'tiger', 'leopard', 'bison']