I've skimmed through the book before, but the content was good, but I felt it was difficult for me to understand because I lacked the skills. I was thinking of watching it again after a long time, and I ended up watching it because there was a video. The author is not only a book, but also has a way of explaining, appropriate examples, and clear planning for delivery.!! How does he explain it so well? I can't help but be impressed by how he explains it so that it's completely understandable in the video lecture. How can I explain that subtle difference? I'm captivated by his skill in explaining it so that I can't help but watch the video over and over again.