}

  // Features

  private final Set<Feature<?>> features = new LinkedHashSet<>();

  /**
   * Configures this builder to produce tests appropriate for the given features. This method may be
   * called more than once to add features in multiple groups.
   */
  @CanIgnoreReturnValue
  public B withFeatures(Feature<?>... features) {
    return withFeatures(asList(features));
  }

  @CanIgnoreReturnValue

              }
            };
          }
        },
        "HashMap w/out null values",
        ALLOWS_NULL_KEYS);
  }

  /**
   * Map generator that verifies that {@code setUp()} methods are called in all the test cases. The
   * {@code setUpRan} parameter is set true by the {@code setUp} that every test case is supposed to
   * have registered, and set false by the {@code tearDown}. We use a dynamic proxy to intercept all

  }

  Stopwatch(Ticker ticker) {
    this.ticker = checkNotNull(ticker, "ticker");
  }

  /**
   * Returns {@code true} if {@link #start()} has been called on this stopwatch, and {@link #stop()}
   * has not been called since the last call to {@code start()}.
   */
  public boolean isRunning() {
    return isRunning;
  }

  /**
   * Starts the stopwatch.
   *

// client did not calculate sha256 of the payload and there is a trailer.
const unsignedPayloadTrailer = "STREAMING-UNSIGNED-PAYLOAD-TRAILER"

// skipContentSha256Cksum returns true if caller needs to skip
// payload checksum, false if not.
func skipContentSha256Cksum(r *http.Request) bool {
	var (
		v  []string
		ok bool
	)

	if isRequestPresignedSignatureV4(r) {

	}

	// There are two possibilities:
	// - We use a KMS -> There must be non-empty key ID and a KMS data key.
	// - We use a K/V -> There must be no key ID and no KMS data key.
	// Otherwise, the caller has passed an invalid argument combination.
	if keyID == "" && len(kmsKey) != 0 {
		logger.CriticalIf(context.Background(), errors.New("The key ID must not be empty if a KMS data key is present"))
	}

	}

	// There are two possibilities:
	// - We use a KMS -> There must be non-empty key ID and a KMS data key.
	// - We use a K/V -> There must be no key ID and no KMS data key.
	// Otherwise, the caller has passed an invalid argument combination.
	if keyID == "" && len(kmsKey) != 0 {
		logger.CriticalIf(context.Background(), errors.New("The key ID must not be empty if a KMS data key is present"))
	}

This practice is common enough that it has a name, these environment variables are commonly placed in a file `.env`, and the file is called a "dotenv".

/// tip

A file starting with a dot (`.`) is a hidden file in Unix-like systems, like Linux and macOS.

But a dotenv file doesn't really have to have that exact filename.

///

    hasher.putBytes(bytes, off, len);
    out.write(bytes, off, len);
  }

  /**
   * Returns the {@link HashCode} based on the data written to this stream. The result is
   * unspecified if this method is called more than once on the same instance.
   */
  public HashCode hash() {
    return hasher.hash();
  }

  // Overriding close() because FilterOutputStream's close() method pre-JDK8 has bad behavior:

abstract class AbstractIndexedListIterator<E extends @Nullable Object>
    extends UnmodifiableListIterator<E> {
  private final int size;
  private int position;

  /** Returns the element with the specified index. This method is called by {@link #next()}. */
  @ParametricNullness
  protected abstract E get(int index);

  /**
   * Constructs an iterator across a sequence of the given size whose initial position is 0. That

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="7"
{!> ../../docs_src/request_forms/tutorial001.py!}
```

////

For example, in one of the ways the OAuth2 specification can be used (called "password flow") it is required to send a `username` and `password` as form fields.

The <abbr title="specification">spec</abbr> requires the fields to be exactly named `username` and `password`, and to be sent as form fields, not JSON.