with proper arguments

$//$ Write your response here.

$[1$Mark$]$

InitbuttonInterrupt$()$;$//$ Initialize external interrupt for the button sei$()$; $//$ Enable global interrupts

while $(1)\{$

$//$ Increase brightness gradually from $75\%$ to $100\%$; and then decrease the brightness gradually from $100\%$ to $50\%.$ You may use for loops to increase and decrease the brightness gradually. $[3$ Marks$]$

$//$ Write your response here.