Doubt in Advance Learning Algorithm course's week 3 lab

In one of the optional labs, I’m getting the following error :-

Please help me to fix it…

Please use the “pencil” icon in the thread title, and move your post to the forum for the course you are attending.

You have posted in the “General Discussion” forum, so we don’t have enough information to answer your question.

Which optional lab are you asking about specifically?

Sorry, my bad !
I’m getting this error in the practice assignment of week 3, Q3