import com.google.errorprone.annotations.concurrent.GuardedBy;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.RetainedWith;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import java.util.logging.Level;
import org.jspecify.annotations.Nullable;

/**

 *
 * <p>This interface is now a legacy type. Use {@code java.util.function.Predicate} (or the
 * appropriate primitive specialization such as {@code IntPredicate}) instead whenever possible.
 * Otherwise, at least reduce <i>explicit</i> dependencies on this type by using lambda expressions
 * or method references instead of classes, leaving your code easier to migrate in the future.
 *

  }

  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
    return new SynchronizedDeque<>(deque, mutex);
  }

  static final class SynchronizedDeque<E extends @Nullable Object> extends SynchronizedQueue<E>
      implements Deque<E> {

    SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
      super(delegate, mutex);
    }

  }

  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
    return new SynchronizedDeque<>(deque, mutex);
  }

  static final class SynchronizedDeque<E extends @Nullable Object> extends SynchronizedQueue<E>
      implements Deque<E> {

    SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
      super(delegate, mutex);
    }

3. **Actively collaborate with us.** We commit real time and...

/**
 * One or more variables that together maintain an initially zero {@code long} sum. When updates
 * (method {@link #add}) are contended across threads, the set of variables may grow dynamically to
 * reduce contention. Method {@link #sum} (or, equivalently, {@link #longValue}) returns the current
 * total combined across the variables maintaining the sum.
 *

 *
 * <p>This interface is now a legacy type. Use {@code java.util.function.Supplier} (or the
 * appropriate primitive specialization such as {@code IntSupplier}) instead whenever possible.
 * Otherwise, at least reduce <i>explicit</i> dependencies on this type by using lambda expressions
 * or method references instead of classes, leaving your code easier to migrate in the future.
 *

   - Use `[WIP]` for in-progress PRs to avoid premature merging or choose GitHub draft PRs.

2. **Commits**:
   - Write clear messages: what changed and why (e.g., “Refactor S3 API handler to reduce latency so that requests process 20% faster”).
   - Rebase to tidy commits before submitting (e.g., `git rebase -i main` to squash typos or reword messages), unless multiple contributors worked on the branch.

import com.google.common.annotations.VisibleForTesting;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Closeable;
import java.io.IOException;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.logging.Level;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Closeable} that collects {@code Closeable} resources and closes them all when it is

/// warning | Попередження

Додаткові допоміжні функції `fake_password_hasher` і `fake_save_user` лише демонструють можливий потік даних і, звісно, не забезпечують реальної безпеки.

///

## Зменшення дублювання { #reduce-duplication }

Зменшення дублювання коду - одна з ключових ідей у **FastAPI**.