docs/code-comparisons/langchain_snippets/lcel_invoke.py

from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.runnables import RunnablePassthrough
from langchain_openai import ChatOpenAI

prompt = ChatPromptTemplate.from_template(
    "Tell me a short joke about {topic}")
output_parser = StrOutputParser()
model = ChatOpenAI(model="gpt-3.5-turbo")
chain = (
    {"topic": RunnablePassthrough()}
    | prompt
    | model
    | output_parser
)
if __name__ == "__main__":
    print(chain.invoke("ice cream"))