[Question] Adding a password to a menu system

code = "codeone"

function cls()
    term.clear()
    term.setCursorPos(1,1)
end

function nuclearReactor()
    cls()
    print("-------------------")
    print("Nuclear menu:")
    print("To turn the reactor on, type 'on'.nTo turn the reactor off, type 'off'.")
    print("To return to the main menu, type exit.")
    print("-------------------")
    write(" > ")
    input = string.lower(read())
    if input == "off" then
        rs.setOutput("left", true)
        print("n----------------")
        print("You have chosen to turn off the nuclear reactor.")
        sleep(2.5) return nuclearReactor()
    elseif input == "on" then
        rs.setOutput("left", false)
        print("n----------------")
        print("You have chosen to turn on the nuclear reactor.")
        sleep(2.5) return nuclearReactor()
    elseif input == "exit" then main()
    else return nuclearReactor()
    end
end

function forceField()
    cls()
    print("-----------------")
    print("Forcefield menu:")
    print("To turn on forcefield, type 'on'.nTo turn it off, type 'off'")
    print("To exit to the main menu, type 'exit'")
    print("-----------------")
    write(" > ")
    input = string.lower(read())
    if input == "on" then
        rs.setOutput("right",true)
        print("n------------------")
        print("Forcefields: Operational")
        sleep(2.5) return forceField()
    elseif input == "off" then
        rs.setOutput("right",false)
        print("n------------------")
        print("Forcefields: Non-Operational")
        sleep(2.5) return forceField()
    elseif input == "exit" then main()
    else return forceField()
    end
end

function menu()
    cls()
    print("--------------------")
    print("TownyHub main menu:")
    print("Enter 'nuclear' for nuclear management.")
    print("Enter 'forcefield' for forcefield management.")
    print("Enter 'exit' to go back to the previous menu.")
    print("Choose an option now, please.")
    print("--------------------")
    write(" > "
    op = string.lower(io.read())
    if op == "nuclear" then nuclearReactor()
    elseif op == "forcefield" then forceField()
    elseif op == "exit" then return
    else return menu()
    end
end

function main()
    cls()
    print("Enter access code:")
    write(" > ")
    input = read("*")
    if input == code then
        menu()
    else
        print("nIncorrect access code!")
        sleep(2)
        return main()
    end
end

-- Clean up
term.clear()
term.setCursorPos(1,1)