}
    }

    for (i in FLAGS.indices) { // Fill in holes with binary representation.
      if (FLAGS[i] == null) FLAGS[i] = BINARY[i]
    }
  }

  /**
   * Returns a human-readable representation of HTTP/2 frame headers.
   *
   * The format is:
   *
   * ```
   * direction streamID length type flags
   * ```
   *
   * Where direction is `<<` for inbound and `>>` for outbound.