this.infiniteCandidates = infiniteCandidates.iterator();
    }

    @Override
    protected Set<E> delegate() {
      return infiniteCandidates.next();
    }
  }

  private static final class MutatedOnQueryList<E> extends ForwardingList<E> {
    final Iterator<ImmutableList<E>> infiniteCandidates;

    if (map.containsKey(key)) {
      // When a collision happens, the colliding entry is the first entry
      // of the tail map.
      Entry<K, V> previousEntry = map.tailMap(key).entrySet().iterator().next();
      throw new IllegalArgumentException(
          "Duplicate keys in mappings "
              + previousEntry.getKey()
              + "="
              + previousEntry.getValue()
              + " and "

    public boolean hasNext() {
      checkModCount();
      nextNotInSkipMe(cursor + 1);
      return (nextCursor < size()) || ((forgetMeNot != null) && !forgetMeNot.isEmpty());
    }

    @Override
    public E next() {
      checkModCount();
      nextNotInSkipMe(cursor + 1);
      if (nextCursor < size()) {
        cursor = nextCursor;
        canRemove = true;
        return elementData(cursor);

    filtered.put("a", 2);
    filtered.put("b", 4);
    assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);

    Entry<String, Integer> entry = filtered.entrySet().iterator().next();
    assertThrows(IllegalArgumentException.class, () -> entry.setValue(5));

    assertEquals(ImmutableMap.of("a", 2, "b", 4), filtered);
  }

  public void testFilteredValuesClear() {

// indicates readDirFn to return without further applying the fn()
var errDoneForNow = errors.New("done for now")

// errSkipFile returned by the fn() for readDirFn() when it needs
// to proceed to next entry.
var errSkipFile = errors.New("skip this file")

var errIgnoreFileContrib = errors.New("ignore this file's contribution toward data-usage")

// errXLBackend XL drive mode requires fresh deployment.

  // Specifies how to treat concurrent executions of a Job.
  // Valid values are:
  //
  // - "Allow" (default): allows CronJobs to run concurrently;
  // - "Forbid": forbids concurrent runs, skipping next run if previous run hasn't finished yet;
  // - "Replace": cancels currently running job and replaces it with a new one
  // +optional
  optional string concurrencyPolicy = 3;

  public E higher(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, false), null);
  }

  @Override
  public E first() {
    return iterator().next();
  }

  @Override
  public E last() {
    return descendingIterator().next();
  }

  /**
   * Guaranteed to throw an exception and leave the set unmodified.
   *
   * @since 12.0
   * @throws UnsupportedOperationException always

    if (e is ProtocolException) {
      return false
    }

    // If there was an interruption don't recover, but if there was a timeout connecting to a route
    // we should try the next route (if there is one).
    if (e is InterruptedIOException) {
      return e is SocketTimeoutException && !requestSendStarted
    }

obvious how environment variables would be useful and applicable right away. But they keep showing up in many different scenarios when you are developing, so it's good to know about them.

For example, you will need this information in the next section, about [Virtual Environments](virtual-environments.md)....

}

// Borrowed from rwmutex_test.go
func benchmarkRWMutex(b *testing.B, localWork, writeRatio int) {
	b.ResetTimer()
	b.ReportAllocs()

	b.RunParallel(func(pb *testing.PB) {
		foo := 0
		for pb.Next() {
			rwm := NewDRWMutex(ds, "test")
			foo++
			if foo%writeRatio == 0 {
				rwm.Lock(id, source)
				rwm.Unlock(context.Background())
			} else {
				rwm.RLock(id, source)