3 stage backlight script

#!/bin/bash

CURRENT=$(cat /sys/class/backlight/intel_backlight/brightness)
LOW='15'
MED='35'
HIGH='100'

if
    [ $CURRENT -eq $LOW ]
    then
    echo "35" > /sys/class/backlight/intel_backlight/brightness
    else
        if
            [ $CURRENT -eq $MED ]
            then
            echo "100" > /sys/class/backlight/intel_backlight/brightness
            else
                if
                    [ $CURRENT -eq $HIGH ]
                                then
                                echo "15" > /sys/class/backlight/intel_backlight/brightness
                            fi
        fi
fi