```Python
async with lifespan(app):
    await do_stuff()
```

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

In our code example above, we don't use it directly, but we pass it to FastAPI for it to use it.

    line-height: normal;
    font-weight: bold;
}

button.dl {
  font-weight: 300;
  font-size: 25px;
  line-height: 40px;
  padding: 3px 10px;
  display: inline-block;
  border-radius: 6px;
  color: #f0f0f0;
  margin: 5px 0;
  width: auto;
}

.logo {
  text-align: center;
  margin-top: 150px;

package once

// Singleton contains a pointer to T that must be set once.
// Until the value is set all Get() calls will block.
type Singleton[T any] struct {
	v   *T
	set chan struct{}
}

// NewSingleton creates a new unset singleton.
func NewSingleton[T any]() *Singleton[T] {
	return &Singleton[T]{set: make(chan struct{}), v: nil}
}

// Get will return the singleton value.
func (s *Singleton[T]) Get() *T {
	<-s.set
	return s.v

   * Queue<E> queue = Queues.synchronizedQueue(MinMaxPriorityQueue.<E>create());
   * ...
   * queue.add(element); // Needn't be in synchronized block
   * ...
   * synchronized (queue) { // Must synchronize on queue!
   *   Iterator<E> i = queue.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
   * }
   *

  @Override
  public boolean offer(E e, long timeout, TimeUnit unit) {
    checkNotNull(unit);
    return offer(e); // never need to block
  }

  /**
   * Inserts the specified element into this priority queue. As the queue is unbounded this method
   * will never block.
   *
   * @param e the element to add
   * @throws ClassCastException if the specified element cannot be compared with elements currently

	shuffledDisks := shuffleDisks(disks, distribution)
	// From the "distribution" above you can notice that:
	// 1st data block is in the 9th disk (i.e distribution index 8)
	// 2nd data block is in the 8th disk (i.e distribution index 7) and so on.
	if shuffledDisks[0] != disks[8] ||
		shuffledDisks[1] != disks[7] ||
		shuffledDisks[2] != disks[9] ||

   * window sufficient to send [byteCount], the caller will block. For example, a user of
   * `HttpURLConnection` who flushes more bytes to the output stream than the connection's write
   * window will block.
   *
   * Zero [byteCount] writes are not subject to flow control and will not block. The only use case
   * for zero [byteCount] is closing a flushed output stream.
   */

/*
 * Copyright (c) 2022 Block, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"os"
	"syscall"
)

var (
	// Disallow updating access times
	// Add non-block to avoid syscall to attempt to set epoll on files.
	readMode = os.O_RDONLY | 0x40000 | syscall.O_NONBLOCK // O_NOATIME

	// Write with data sync only used only for `xl.meta` writes

        title.appendChild(literal);
        literal.appendChild(document.createTextNode(blockDoc.getName()));
        title.appendChild(document.createTextNode(" { }"));

        warningsRenderer.renderTo(blockDoc, "script block", section);

        for (Element element : blockDoc.getComment()) {
            section.appendChild(document.importNode(element, true));
        }

        Element segmentedlist = document.createElement("segmentedlist");