app.py

import streamlit as st

#Globals
legal_numbers = [1,2,3,4,5,6,7,8,9]

def get_userInput(): 
    input = st.text_input("Enter a number between 1 to 9: ", key="input")
    return input

def validate_userInput(user_input):
    if user_input.isdigit():
        if int(user_input) < 1 or int(user_input) > 9:
            return False
        else:    
            return True
    else:
        return False

def error_Message(msg):
    st.write(msg)

def display_board(firstRun):  
    if firstRun:
        col1, col2, col3 = st.columns(3)
        col4, col5, col6 = st.columns(3)
        col7, col8, col9 = st.columns(3)
        with col1:
            st.text("X")
        with col2:
           st.text("O")
        with col3:
           st.text("...")
        with col4:
            st.text(" X ")
        with col5:
           st.text(" O ")
        with col6:
           st.text(" ... ")
        with col7:
            st.text(" X ")
        with col8:
           st.text(" O ")
        with col9:
           st.text(" ... ")
 #   else:
        

def reset_legalNumbers():
    legal_numbers = [1,2,3,4,5,6,7,8,9]
    
def update_legalNumbers(number):
    legal_numbers.remove(int(user_input))
    #st.text("Legal Numbers: " + "".join(str(legal_numbers)))
    print(legal_numbers)

#UIApp starts here
st.set_page_config(page_title="Python - Tic Tac Toe", page_icon=":python:")
st.header("Python - Tic Tac Toe")

user_input=get_userInput()
display_board(True)

firstRun=True
if firstRun:
    reset_legalNumbers()
    firstRun=False

#UI Buttons
submit=st.button('Submit')
replay=st.button('Replay')

#Button functionality
if submit:
    response=validate_userInput(user_input)
    if response:
        update_legalNumbers(user_input)
    else:
         error_Message("Please enter a digit between 1 to 9.")

if replay:
    display_board(True)
    #reset_legalNumbers()