In support to blog post

RetainCycle8.swift

class HTMLElement {
    ...
    
    lazy var asHTML: () -> String = { [weak self] in
        guard let htmlElement = self else { return "" }
        return "<\(htmlElement.name)>\(htmlElement.text)</\(htmlElement.name)>"
    }
    
    ...
}

var paragraph: HTMLElement? = HTMLElement(name: "p", text: "hello, world")
paragraph?.asHTML()
paragraph = nil

// Output:
// HTMLElement p is being deinitialized