def parse_turn(turn):
    """Parse the input from the user for valid player strings and play positions
    Args:
        turn (string): Input string from the user that contains the played
                       position (0-8)

    Returns:
        (int/None): Returns interger on success or None on failure
    """
    try:
        # check if position is valid
        if int(turn) > 8 or int(turn) < 0:
            print("Position must be 0-8")
            return None
        return int(turn)
    except Exception as e:
        print("Could not parse position")
        return None