Help: streamlit-webrtc key assignment not working

Custom Components streamlit-webrtc
1 
import streamlit as st
from streamlit_webrtc import webrtc_streamer
from git import Repo
import arrow
import os

.
.
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if "page" not in st.session_state:
    st.session_state = "Home"
with st.sidebar:
    if st.button(label="Home", icon="🏠", use_container_width=True):
        st.session_state = "Home"
    if st.button(label="FAQ", icon="❓", use_container_width=True):
        st.session_state = "FAQ"
    if st.button(label="Options", icon="⚙️", use_container_width=True):
        st.session_state = "Options"
    show_sidebar_footer()
if st.session_state == "Home":
    st.title("Home")
    webrtc_streamer(key="example")
if st.session_state == "FAQ":
    st.title("FAQ")
if st.session_state == "Options":
    st.title("Options")

st.session_state[key] = context
~~~~~~~~~~~~~~~~^^^^^
TypeError: ‘str’ object does not support item assignment

This is my code, when I run it the streamlit-webrtc gives error. How do i fix?