About line follower robots

Hey there
I want you help me to understand the code of this line follower robot ,i have done the basic line follower robot but cant make this one
the youtube link:

I want you help me to understand the code of this line follower robot

I can't see any code.

yes he refuse to send the code so i want write it

so i want write it

Permission granted. Proceed.

What part(s) are you having problems with? What part(s) are working?

Thank you for your reply

the part of changing the leds color when it detect an external line and take an action depended on it

the part of changing the leds color when it detect an external line

So, you know how to detect a line, but you can't change the color of an LED? Amazing.

do you watch the video dude?? is he use another tracking sensor for the external line or what ?? I want to use one sensor only

do you watch the video dude??

Yes, I did.

is he use another tracking sensor for the external line or what ??

Obviously, he is using more than one sensor. A line following robot always uses at least two. Usually 3 or 5. Otherwise, it is difficult to follow the line with any speed.

I want to use one sensor only

Might I humbly suggest that you get over it.

Look at this: https://www.pololu.com/docs/0J19/all