# Copyright 2023 The TensorFlow Authors. All Rights Reserved.
#
# 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,

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

	Importpath = flag.String("p", obj.UnlinkablePkg, "set expected package import to path")
	Spectre    = flag.String("spectre", "", "enable spectre mitigations in `list` (all, ret)")
)

var DebugFlags struct {
	MayMoreStack string `help:"call named function before all stack growth checks"`
	PCTab        string `help:"print named pc-value table\nOne of: pctospadj, pctofile, pctoline, pctoinline, pctopcdata"`
}

var (
	D        MultiFlag

      Byte[] all = concat(elements, suffix);
      return asList(all).subList(0, elements.length);
    }
  }

  public static final class BytesAsListTailSubListGenerator extends TestByteListGenerator {
    @Override
    protected List<Byte> create(Byte[] elements) {
      Byte[] prefix = {(byte) 86, (byte) 99};
      Byte[] all = concat(prefix, elements);

      Long[] all = concat(elements, suffix);
      return asList(all).subList(0, elements.length);
    }
  }

  public static final class LongsAsListTailSubListGenerator extends TestLongListGenerator {
    @Override
    protected List<Long> create(Long[] elements) {
      Long[] prefix = {(long) 86, (long) 99};
      Long[] all = concat(prefix, elements);

  /** A bit mask which selects the bit encoding ASCII character case. */
  private static final char CASE_MASK = 0x20;

  /**
   * Returns a copy of the input string in which all {@linkplain #isUpperCase(char) uppercase ASCII
   * characters} have been converted to lowercase. All other characters are copied without
   * modification.
   */
  public static String toLowerCase(String string) {
    int length = string.length();

In many frameworks and systems just handling security and authentication takes a big amount of effort and code (in many cases it can be 50% or more of all the code written).

**FastAPI** provides several tools to help you deal with **Security** easily, rapidly, in a standard way, without having to study and learn all the security specifications.

But first, let's check some small concepts.

## In a hurry?

   *   remove(K, long). Without any two-phase operations it becomes feasible for all remaining
   *   operations to distinguish between zero and absent. If we do this, then perhaps we should add
   *   replace(key, long).
   *
   * - Introduce a special-value private static final AtomicLong that would have the meaning of
   *   removal-in-progress, and rework all operations to properly distinguish between zero and
   *   absent.
   */

   * input futures, if all succeed.
   *
   * <p>The list of results is in the same order as the input list.
   *
   * <p>This differs from {@link #successfulAsList(ListenableFuture[])} in that it will return a
   * failed future if any of the items fails.
   *
   * <p>Canceling this future will attempt to cancel all the component futures, and if any of the

 *
 * <p>The methods returning collections or maps always return views of the underlying table.
 * Updating the table can change the contents of those collections, and updating the collections
 * will change the table.
 *
 * <p>All methods that modify the table are optional, and the views returned by the table may or may
 * not be modifiable. When modification isn't supported, those methods will throw an {@link
 * UnsupportedOperationException}.
 *