if X > 0 then
Y := 0;
end if;
Like this, except replace "..." with many lines of code.
if (z.p == z.p.p.left) {
...
} else { // z.p != z.p.p.left
...
} // ifTrue. However, in Ada at least, if the block types don't match then it's a syntax error detected at compile time by the compiler. Comments like those listed above are often not checked at compile time, and thus aren't very useful for preventing errors.
Often it's only for named blocks like functions, and not for the really unhelpful bits like that conditional branch that is long, simple and deep, but really does not deserve spamming a namespace with an unhelpful identifier. And I've yet to see a deliberately short-lived folding to lessen the out of sight, out of mind tax that code folding of associated with. If there was deliberately short-lived folding, perhaps auto-reexpanding whenever the section has scrolled out of view, I'd use folding all the time, to navigate the nesting. The quasi-permanent until explicitly re-expanded cold folding? Yeah, I hardly ever use it, to many bad experiences with forgetting to re-expand.
Perhaps new generation of editors ("post VSC") that experiments with non-uniform size could perhaps lead to some form of revival? Fold to "code minimap" excerpt instead of away. UI might want to consider cursor position in the leading whitespace for depth selection. In mouse terms, interact with the vertical line some editors display (not sure this could be helpful for keyboard knowitalls who'd select depth by repetition)
Or maybe this all exists but the shortcuts aren't sufficiently well known to reach my lowly knowledge levels, that's one of the more frustrating aspects of what-iffing editor UI.
The reverse-reserved-word convention like ‘fi’ to end an if block in shell (and other?) languages seems like it functions this way too.
And I guess significant indentation also does this job, albeit with some of its own hazards.