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It's been awhile since I wrote about FOUCE and I've since come up with an improved solution that I think is worth a post. This approach is similar to hiding the page content and then fading it in, but I've noticed it's far less distracting without the fade. It also adds a two second timeout to prevent network issues or latency from rendering an "empty" page. First, we'll add a class called reduce-fouce to the <html> element. <html class="reduce-fouce"> ... </html> Then we'll add this rule to the CSS. <style> html.reduce-fouce { opacity: 0; } </style> Finally, we'll wait until all the custom elements have loaded or two seconds have elapsed, whichever comes first, and we'll remove the class causing the content to show immediately. <script type="module"> await Promise.race([ // Load all custom elements Promise.allSettled([ customElements.whenDefined('my-button'), customElements.whenDefined('my-card'), customElements.whenDefined('my-rating') // ... ]), // Resolve after two seconds new Promise(resolve => setTimeout(resolve, 2000)) ]); // Remove the class, showing the page content document.documentElement.classList.remove('reduce-fouce'); </script> This approach seems to work especially well and won't end up "stranding" the user if network issues occur.
Once upon a midnight dreary, while I pondered, weak and weary, While I nodded, nearly napping, suddenly there came a tapping, "'Tis a design system," I muttered, "bringing order to the core— Ah, distinctly I remember, every button, every splendor, Each component, standardized, like a raven's watchful eyes, Unified in system's might, like patterns we restore— And each separate style injection, linked with careful introspection, 'Tis a design system, nothing more.
It’s disappointing that some of the most outspoken individuals against Web Components are framework maintainers. These individuals are, after all, in some of the best positions to provide valuable feedback. They have a lot of great ideas! Alas, there’s little incentive for them because standards evolve independently and don’t necessarily align with framework opinions. How could they? Opinions are one of the things that make frameworks unique. And therein lies the problem. If you’re convinced that your way is the best and only way, it’s natural to feel disenchanted when a decision is made that you don’t fully agree with. This is my open response to Ryan Carniato’s post from yesterday called “Web Components Are Not the Future.” WTF is a component anyway? # The word component is a loaded term, but I like to think of it in relation to interoperability. If I write a component in Framework A, I would like to be able to use it in Framework B, C, and D without having to rewrite it or include its entire framework. I don’t think many will disagree with that objective. We’re not there yet, but the road has been paved and instead of learning to drive on it, frameworks are building…different roads. Ryan states: If the sheer number of JavaScript frameworks is any indicator we are nowhere near reaching a consensus on how one should author components on the web. And even if we were a bit closer today we were nowhere near there a decade ago. The thing is, we don’t need to agree on how to write components, we just need to agree on the underlying implementation, then you can use classes, hooks, or whatever flavor you want to create them. Turns out, we have a very well-known, ubiquitous technology that we’ve chosen to do this with: HTML. But it also can have a negative effect. If too many assumptions are made it becomes harder to explore alternative space because everything gravitates around the establishment. What is more established than a web standard that can never change? If the concern is premature standardization, well, it’s a bit late for that. So let’s figure out how to get from where we are now to where we want to be. The solution isn’t to start over at the specification level, it’s to rethink how front end frameworks engage with current and emerging standards and work to improve them. Respectfully, it’s time to stop complaining, move on, and fix the things folks perceive as suboptimal. The definition of component # That said, we also need to realize that Web Components aren’t a 1:1 replacement for framework components. They’re tangentially related things, and I think a lot of confusion stems from this. We should really fix the definition of component. So the fundamental problem with Web Components is that they are built on Custom Elements. Elements !== Components. More specifically, Elements are a subset of Components. One could argue that every Element could be a Component but not all Components are Elements. To be fair, I’ve never really liked the term “Web Components” because it competes with the concept of framework components, but that’s what caught on and that's what most people are familiar with these days. Alas, there is a very important distinction here. Sure, a button and a text field can be components, but there are other types. For example, many frameworks support a concept of renderless components that exist in your code, but not in the final HTML. You can’t do that with Web Components, because every custom element results in an actual DOM element. (FWIW I don’t think this is a bad thing — but I digress…) As to why Web components don’t do all the things framework components do, that’s because they’re a lower level implementation of an interoperable element. They’re not trying to do everything framework components do. That’s what frameworks are for. It’s ok to be shiny # In fact, this is where frameworks excel. They let you go above and beyond what the platform can do on its own. I fully support this trial-and-error way of doing things. After all, it’s fun to explore new ideas and live on the bleeding edge. We got a lot of cool stuff from doing that. We got document.querySelector() from jQuery. CSS Custom Properties were inspired by Sass. Tagged template literals were inspired by JSX. Soon we’re getting signals from Preact. And from all the component-based frameworks that came before them, we got Web Components: custom HTML elements that can be authored in many different ways (because we know people like choices) and are fully interoperable (if frameworks and metaframeworks would continue to move towards the standard instead of protecting their own). Frameworks are a testbed for new ideas that may or may not work out. We all need to be OK with that. Even framework authors. Especially framework authors. More importantly, we all need to stop being salty when our way isn’t what makes it into the browser. There will always be a better way to do something, but none of us have the foresight to know what a perfect solution looks like right now. Hindsight is 20/20. As humans, we’re constantly striving to make things better. We’re really good at it, by the way. But we must have the discipline to reach various checkpoints to pause, reflect, and gather feedback before continuing. Even the cheapest cars on the road today will outperform the Model T in every way. I’m sure Ford could have made the original Model T way better if they had spent another decade working on it, but do you know made the next version even better than 10 more years? The feedback they got from actual users who bought them, sat in them, and drove them around on actual roads. Web Standards offer a promise of stability and we need to move forward to improve them together. Using one’s influence to rally users against the very platform you’ve built your success on is damaging to both the platform and the community. We need these incredible minds to be less divisive and more collaborative. The right direction # Imagine if we applied the same arguments against HTML early on. What if we never standardized it at all? Would the Web be a better place if every site required a specific browser? (Narrator: it wasn't.) Would it be better if every site was Flash or a Java applet? (Remember Silverlight? lol) Sure, there are often better alternatives for every use case, but we have to pick something that works for the majority, then we can iterate on it. Web Components are a huge step in the direction of standardization and we should all be excited about that. But the Web Component implementation isn’t compatible with existing frameworks, and therein lies an existential problem. Web Components are a threat to the peaceful, proprietary way of life for frameworks that have amassed millions of users — the majority of web developers. Because opinions vary so wildly, when a new standard emerges frameworks can’t often adapt to them without breaking changes. And breaking changes can be detrimental to a user base. Have you spotted the issue? You can’t possibly champion Web Standards when you’ve built a non-standard thing that will break if you align with the emerging standard. It’s easier to oppose the threat than to adapt to it. And of course Web Components don’t do everything a framework does. How can the platform possibly add all the features every framework added last week? That would be absolutely reckless. And no, the platform doesn’t move as fast as your framework and that’s sometimes painful. But it’s by design. This process is what gives us APIs that continue to work for decades. As users, we need to get over this hurdle and start thinking about how frameworks can adapt to current standards and how to evolve them as new ones emerge. Let’s identify shortcomings in the spec and work together to improve the ecosystem instead of arguing about who’s shit smells worse. Reinventing the wheel isn’t the answer. Lock-in isn’t the answer. This is why I believe that next generation of frameworks will converge on custom elements as an interoperable component model, enhance that model by sprinkling in awesome features of their own, and focus more on flavors (class-based, functional, signals, etc.) and higher level functionality. As for today's frameworks? How they adapt will determine how relevant they remain. Living dangerously # Ryan concludes: So in a sense there are nothing wrong with Web Components as they are only able to be what they are. It's the promise that they are something that they aren't which is so dangerous. The way their existence warps everything around them that puts the whole web at risk. It's a price everyone has to pay. So Web Components aren’t the specific vision you had for components. That's fine. But that's how it is. They're not Solid components. They’re not React components. They’re not Svelte components. They’re not Vue components. They’re standards-based Web Components that work in all of the above. And they could work even better in all of the above if all of the above were interested in advancing the platform instead of locking users in. I’m not a conspiracy theorist, but I find interesting the number of people who are and have been sponsored and/or hired by for-profit companies whose platforms rely heavily on said frameworks. Do you think it’s in their best interest to follow Web Standards if that means making their service less relevant and less lucrative? Of course not. If you’ve built an empire on top of something, there’s absolutely zero incentive to tear it down for the betterment of humanity. That’s not how capitalism works. It’s far more profitable to lock users in and keep them paying. But you know what…? Web Standards don't give a fuck about monetization. Longevity supersedes ingenuity # The last thing I’d like to talk about is this line here. Web Components possibly pose the biggest risk to the future of the web that I can see. Of course, this is from the perspective of a framework author, not from the people actually shipping and maintaining software built using these frameworks. And the people actually shipping software are the majority, but that’s not prestigious so they rarely get the high follower counts. The people actually shipping software are tired of framework churn. They're tired of shit they wrote last month being outdated already. They want stability. They want to know that the stuff they build today will work tomorrow. As history has proven, no framework can promise that. You know what framework I want to use? I want a framework that aligns with the platform, not one that replaces it. I want a framework that values incremental innovation over user lock-in. I want a framework that says it's OK to break things if it means making the Web a better place for everyone. Yes, that comes at a cost, but almost every good investment does, and I would argue that cost will be less expensive than learning a new framework and rebuilding buttons for the umpteenth time. The Web platform may not be perfect, but it continuously gets better. I don’t think frameworks are bad but, as a community, we need to recognize that a fundamental piece of the platform has changed and it's time to embrace the interoperable component model that Web Component APIs have given us…even if that means breaking things to get there. The component war is over.
Components are like little machines. You build them once. Use them whenever you need them. Every now and then you open them up to oil them or replace a part, then you send them back to work. And work, they do. Little component machines just chugging along so you never have to write them from scratch ever again. Adapted from this tweet.
I've been struggling with the idea of reflecting attributes in custom elements and when it's appropriate. I think I've identified a gap in the platform, but I'm not sure exactly how we should fill it. I'll explain with an example. Let's say I want to make a simple badge component with primary, secondary, and tertiary variants. <my-badge variant="primary">foo</my-badge> <my-badge variant="secondary">bar</my-badge> <my-badge variant="tertiary">baz</my-badge> This is a simple component, but one that demonstrates the problem well. I want to style the badge based on the variant property, but sprouting attributes (which occurs as a result of reflecting a property back to an attribute) is largely considered a bad practice. A lot of web component libraries do it out of necessary to facilitate styling — including Shoelace — but is there a better way? The problem # I need to style the badge without relying on reflected attributes. This means I can't use :host([variant="..."]) because the attribute may or may not be set by the user. For example, if the component is rendered in a framework that sets properties instead of attributes, or if the property is set or changed programmatically, the attribute will be out of sync and my styles will be broken. So how can I style the badge based its variants without reflection? Let's assume we have the following internals, which is all we really need for the badge. <my-badge> #shadowRoot <slot></slot> </my-badge> What can we do about it? # I can't add classes to the slot, because :host(:has(.slot-class)) won't match. I can't set a data attribute on the host element, because that's the same as reflection and might cause issues with SSR and DOM morphing libraries. I could add a wrapper element around the slot and apply classes to it, but I'd prefer not to bloat the internals with additional elements. With a wrapper, users would have to use ::part(wrapper) to target it. Without the wrapper, they can set background, border, and other CSS properties directly on the host element which is more desirable. I could add custom states for each variant, but this gets messy for non-Boolean values and feels like an abuse of the API. Filling the gap # I'm not sure what the best solution is or could be, but one thing that comes to mind is a way to provide some kind of cross-root version of :has that works with :host. Something akin to: :host(:has-in-shadow-root(.some-selector)) { /* maybe one day… */ } If you have any thoughts on this one, hit me up on Twitter.
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Here are a few tangentially-related ideas vaguely near the theme of comparison operators. comparison style clamp style clamp is median clamp in range range style style clash? comparison style Some languages such as BCPL, Icon, Python have chained comparison operators, like if min <= x <= max: ... In languages without chained comparison, I like to write comparisons as if they were chained, like, if min <= x && x <= max { // ... } A rule of thumb is to prefer less than (or equal) operators and avoid greater than. In a sequence of comparisons, order values from (expected) least to greatest. clamp style The clamp() function ensures a value is between some min and max, def clamp(min, x, max): if x < min: return min if max < x: return max return x I like to order its arguments matching the expected order of the values, following my rule of thumb for comparisons. (I used that flavour of clamp() in my article about GCRA.) But I seem to be unusual in this preference, based on a few examples I have seen recently. clamp is median Last month, Fabian Giesen pointed out a way to resolve this difference of opinion: A function that returns the median of three values is equivalent to a clamp() function that doesn’t care about the order of its arguments. This version is written so that it returns NaN if any of its arguments is NaN. (When an argument is NaN, both of its comparisons will be false.) fn med3(a: f64, b: f64, c: f64) -> f64 { match (a <= b, b <= c, c <= a) { (false, false, false) => f64::NAN, (false, false, true) => b, // a > b > c (false, true, false) => a, // c > a > b (false, true, true) => c, // b <= c <= a (true, false, false) => c, // b > c > a (true, false, true) => a, // c <= a <= b (true, true, false) => b, // a <= b <= c (true, true, true) => b, // a == b == c } } When two of its arguments are constant, med3() should compile to the same code as a simple clamp(); but med3()’s misuse-resistance comes at a small cost when the arguments are not known at compile time. clamp in range If your language has proper range types, there is a nicer way to make clamp() resistant to misuse: fn clamp(x: f64, r: RangeInclusive<f64>) -> f64 { let (&min,&max) = (r.start(), r.end()); if x < min { return min } if max < x { return max } return x; } let x = clamp(x, MIN..=MAX); range style For a long time I have been fond of the idea of a simple counting for loop that matches the syntax of chained comparisons, like for min <= x <= max: ... By itself this is silly: too cute and too ad-hoc. I’m also dissatisfied with the range or slice syntax in basically every programming language I’ve seen. I thought it might be nice if the cute comparison and iteration syntaxes were aspects of a more generally useful range syntax, but I couldn’t make it work. Until recently when I realised I could make use of prefix or mixfix syntax, instead of confining myself to infix. So now my fantasy pet range syntax looks like >= min < max // half-open >= min <= max // inclusive And you might use it in a pattern match if x is >= min < max { // ... } Or as an iterator for x in >= min < max { // ... } Or to take a slice xs[>= min < max] style clash? It’s kind of ironic that these range examples don’t follow the left-to-right, lesser-to-greater rule of thumb that this post started off with. (x is not lexically between min and max!) But that rule of thumb is really intended for languages such as C that don’t have ranges. Careful stylistic conventions can help to avoid mistakes in nontrivial conditional expressions. It’s much better if language and library features reduce the need for nontrivial conditions and catch mistakes automatically.
After shipping my work transforming HTML with Netlify’s edge functions I realized I have a little bug: the order of the icons specified in the URL doesn’t match the order in which they are displayed on screen. Why’s this happening? I have a bunch of links in my HTML document, like this: <icon-list> <a href="/1/">…</a> <a href="/2/">…</a> <a href="/3/">…</a> <!-- 2000+ more --> </icon-list> I use html-rewriter in my edge function to strip out the HTML for icons not specified in the URL. So for a request to: /lookup?id=1&id=2 My HTML will be transformed like so: <icon-list> <!-- Parser keeps these two --> <a href="/1/">…</a> <a href="/2/">…</a> <!-- But removes this one --> <a href="/3/">…</a> </icon-list> Resulting in less HTML over the wire to the client. But what about the order of the IDs in the URL? What if the request is to: /lookup?id=2&id=1 Instead of: /lookup?id=1&id=2 In the source HTML document containing all the icons, they’re marked up in reverse chronological order. But the request for this page may specify a different order for icons in the URL. So how do I rewrite the HTML to match the URL’s ordering? The problem is that html-rewriter doesn’t give me a fully-parsed DOM to work with. I can’t do things like “move this node to the top” or “move this node to position x”. With html-rewriter, you only “see” each element as it streams past. Once it passes by, your chance at modifying it is gone. (It seems that’s just the way these edge function tools are designed to work, keeps them lean and performant and I can’t shoot myself in the foot). So how do I change the icon’s display order to match what’s in the URL if I can’t modify the order of the elements in the HTML? CSS to the rescue! Because my markup is just a bunch of <a> tags inside a custom element and I’m using CSS grid for layout, I can use the order property in CSS! All the IDs are in the URL, and their position as parameters has meaning, so I assign their ordering to each element as it passes by html-rewriter. Here’s some pseudo code: // Get all the IDs in the URL const ids = url.searchParams.getAll("id"); // Select all the icons in the HTML rewriter.on("icon-list a", { element: (element) => { // Get the ID const id = element.getAttribute('id'); // If it's in our list, set it's order // position from the URL if (ids.includes(id)) { const order = ids.indexOf(id); element.setAttribute( "style", `order: ${order}` ); // Otherwise, remove it } else { element.remove(); } }, }); Boom! I didn’t have to change the order in the source HTML document, but I can still get the displaying ordering to match what’s in the URL. I love shifty little workarounds like this! Email · Mastodon · Bluesky
I realize that for all I've talked about Logic for Programmers in this newsletter, I never once explained basic logical quantifiers. They're both simple and incredibly useful, so let's do that this week! Sets and quantifiers A set is a collection of unordered, unique elements. {1, 2, 3, …} is a set, as are "every programming language", "every programming language's Wikipedia page", and "every function ever defined in any programming language's standard library". You can put whatever you want in a set, with some very specific limitations to avoid certain paradoxes.2 Once we have a set, we can ask "is something true for all elements of the set" and "is something true for at least one element of the set?" IE, is it true that every programming language has a set collection type in the core language? We would write it like this: # all of them all l in ProgrammingLanguages: HasSetType(l) # at least one some l in ProgrammingLanguages: HasSetType(l) This is the notation I use in the book because it's easy to read, type, and search for. Mathematicians historically had a few different formats; the one I grew up with was ∀x ∈ set: P(x) to mean all x in set, and ∃ to mean some. I use these when writing for just myself, but find them confusing to programmers when communicating. "All" and "some" are respectively referred to as "universal" and "existential" quantifiers. Some cool properties We can simplify expressions with quantifiers, in the same way that we can simplify !(x && y) to !x || !y. First of all, quantifiers are commutative with themselves. some x: some y: P(x,y) is the same as some y: some x: P(x, y). For this reason we can write some x, y: P(x,y) as shorthand. We can even do this when quantifying over different sets, writing some x, x' in X, y in Y instead of some x, x' in X: some y in Y. We can not do this with "alternating quantifiers": all p in Person: some m in Person: Mother(m, p) says that every person has a mother. some m in Person: all p in Person: Mother(m, p) says that someone is every person's mother. Second, existentials distribute over || while universals distribute over &&. "There is some url which returns a 403 or 404" is the same as "there is some url which returns a 403 or some url that returns a 404", and "all PRs pass the linter and the test suites" is the same as "all PRs pass the linter and all PRs pass the test suites". Finally, some and all are duals: some x: P(x) == !(all x: !P(x)), and vice-versa. Intuitively: if some file is malicious, it's not true that all files are benign. All these rules together mean we can manipulate quantifiers almost as easily as we can manipulate regular booleans, putting them in whatever form is easiest to use in programming. Speaking of which, how do we use this in in programming? How we use this in programming First of all, people clearly have a need for directly using quantifiers in code. If we have something of the form: for x in list: if P(x): return true return false That's just some x in list: P(x). And this is a prevalent pattern, as you can see by using GitHub code search. It finds over 500k examples of this pattern in Python alone! That can be simplified via using the language's built-in quantifiers: the Python would be any(P(x) for x in list). (Note this is not quantifying over sets but iterables. But the idea translates cleanly enough.) More generally, quantifiers are a key way we express higher-level properties of software. What does it mean for a list to be sorted in ascending order? That all i, j in 0..<len(l): if i < j then l[i] <= l[j]. When should a ratchet test fail? When some f in functions - exceptions: Uses(f, bad_function). Should the image classifier work upside down? all i in images: classify(i) == classify(rotate(i, 180)). These are the properties we verify with tests and types and MISU and whatnot;1 it helps to be able to make them explicit! One cool use case that'll be in the book's next version: database invariants are universal statements over the set of all records, like all a in accounts: a.balance > 0. That's enforceable with a CHECK constraint. But what about something like all i, i' in intervals: NoOverlap(i, i')? That isn't covered by CHECK, since it spans two rows. Quantifier duality to the rescue! The invariant is equivalent to !(some i, i' in intervals: Overlap(i, i')), so is preserved if the query SELECT COUNT(*) FROM intervals CROSS JOIN intervals … returns 0 rows. This means we can test it via a database trigger.3 There are a lot more use cases for quantifiers, but this is enough to introduce the ideas! Next week's the one year anniversary of the book entering early access, so I'll be writing a bit about that experience and how the book changed. It's crazy how crude v0.1 was compared to the current version. MISU ("make illegal states unrepresentable") means using data representations that rule out invalid values. For example, if you have a location -> Optional(item) lookup and want to make sure that each item is in exactly one location, consider instead changing the map to item -> location. This is a means of implementing the property all i in item, l, l' in location: if ItemIn(i, l) && l != l' then !ItemIn(i, l'). ↩ Specifically, a set can't be an element of itself, which rules out constructing things like "the set of all sets" or "the set of sets that don't contain themselves". ↩ Though note that when you're inserting or updating an interval, you already have that row's fields in the trigger's NEW keyword. So you can just query !(some i in intervals: Overlap(new, i')), which is more efficient. ↩
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Kubernetes is not exactly the most fun piece of technology around. Learning it isn’t easy, and learning the surrounding ecosystem is even harder. Even those who have managed to tame it are still afraid of getting paged by an ETCD cluster corruption, a Kubelet certificate expiration, or the DNS breaking down (and somehow, it’s always the DNS). Samuel Sianipar If you’re like me, the thought of making your own orchestrator has crossed your mind a few times. The result would, of course, be a magical piece of technology that is both simple to learn and wouldn’t break down every weekend. Sadly, the task seems daunting. Kubernetes is a multi-million lines of code project which has been worked on for more than a decade. The good thing is someone wrote a book that can serve as a good starting point to explore the idea of building our own container orchestrator. This book is named “Build an Orchestrator in Go”, written by Tim Boring, published by Manning. The tasks The basic unit of our container orchestrator is called a “task”. A task represents a single container. It contains configuration data, like the container’s name, image and exposed ports. Most importantly, it indicates the container state, and so acts as a state machine. The state of a task can be Pending, Scheduled, Running, Completed or Failed. Each task will need to interact with a container runtime, through a client. In the book, we use Docker (aka Moby). The client will get its configuration from the task and then proceed to pull the image, create the container and start it. When it is time to finish the task, it will stop the container and remove it. The workers Above the task, we have workers. Each machine in the cluster runs a worker. Workers expose an API through which they receive commands. Those commands are added to a queue to be processed asynchronously. When the queue gets processed, the worker will start or stop tasks using the container client. In addition to exposing the ability to start and stop tasks, the worker must be able to list all the tasks running on it. This demands keeping a task database in the worker’s memory and updating it every time a task change’s state. The worker also needs to be able to provide information about its resources, like the available CPU and memory. The book suggests reading the /proc Linux file system using goprocinfo, but since I use a Mac, I used gopsutil. The manager On top of our cluster of workers, we have the manager. The manager also exposes an API, which allows us to start, stop, and list tasks on the cluster. Every time we want to create a new task, the manager will call a scheduler component. The scheduler has to list the workers that can accept more tasks, assign them a score by suitability and return the best one. When this is done, the manager will send the work to be done using the worker’s API. In the book, the author also suggests that the manager component should keep track of every tasks state by performing regular health checks. Health checks typically consist of querying an HTTP endpoint (i.e. /ready) and checking if it returns 200. In case a health check fails, the manager asks the worker to restart the task. I’m not sure if I agree with this idea. This could lead to the manager and worker having differing opinions about a task state. It will also cause scaling issues: the manager workload will have to grow linearly as we add tasks, and not just when we add workers. As far as I know, in Kubernetes, Kubelet (the equivalent of the worker here) is responsible for performing health checks. The CLI The last part of the project is to create a CLI to make sure our new orchestrator can be used without having to resort to firing up curl. The CLI needs to implement the following features: start a worker start a manager run a task in the cluster stop a task get the task status get the worker node status Using cobra makes this part fairly straightforward. It lets you create very modern feeling command-line apps, with properly formatted help commands and easy argument parsing. Once this is done, we almost have a fully functional orchestrator. We just need to add authentication. And maybe some kind of DaemonSet implementation would be nice. And a way to handle mounting volumes…
