buying-selling cargo 1 by 1

HotKeySet("{PAUSE}","zzz")
HotKeySet("=","switch_flag_buy")
HotKeySet("-","switch_flag_sell")
Opt("SendKeyDelay",20)
Opt("SendKeyDownDelay",20)
Dim $flag_sell = False
Dim $flag_buy = False

While 1
    $nMsg = GUIGetMsg()
    If $flag_sell Then
        do_routine_sell()
    EndIf
    If $flag_buy Then
        do_routine_buy()
    EndIf
WEnd

func switch_flag_sell()
    $flag_sell = not $flag_sell
    $flag_buy = False
EndFunc

func switch_flag_buy()
    $flag_buy = not $flag_buy
    $flag_sell = False
EndFunc

func do_routine_sell()
    Send(" {LEFT} ")
    Sleep(200)
endfunc

func do_routine_buy()
    Send(" {RIGHT} ")
    Sleep(200)
endfunc

func zzz()
    Exit(0)
endfunc