web.py

import streamlit as st
import functions

todos = functions.get_todos()

def add_todo():
    todo = st.session_state['new_todo'] + '\n'
    todos.append(todo)
    functions.write_todos(todos)


st.title('My To-Do App')
st.subheader('This is my todo app')
st.write('Increase your productivity...')

for index, todo in enumerate(todos):
    checkbox = st.checkbox(todo, key=todo)
    if checkbox:
        todos.pop(index)
        functions.write_todos(todos)
        del st.session_state[todo]
        st.experimental_rerun()

st.text_input(label="Enter a todo: ", placeholder="To-Do",
              on_change=add_todo, key='new_todo')

print("Page Refreshed")
st.session_state