How to copy ContextVar to Streamlit app threads?

Using Streamlit
1

Hi,
My Streamlit app should copy ContextVar. This is a minimal example code for it.

// test.py
// This script is running locally in Python 3.11 and Streamlit 1.32.0
// streamlit run --server.address localhost test.py
import streamlit as st
from contextvars import ContextVar, copy_context

MY_VAR = ContextVar("my_var")
MY_VAR.set("test")


def on_click():
    # LookupError: <ContextVar name='my_var' at 0x7fb7a8333600>
    print(f"MY_VAR: {MY_VAR.get()}")

st.title("Test")
st.button("button", on_click=on_click)

If we click the button in this script, it will get LookupError because the MY_VAR is not copied to the Streamlit thread. Is there any method in Streamlit to copy this context like?

ctx = copy_context()

def init_ctx(ctx):
    for val, value in ctx.items():
        val.set(value)

# There is no function in reality, but to describe my problem
# st.init_thread(init_ctx)
2

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