const val TYPE_RST_STREAM = 0x3
  const val TYPE_SETTINGS = 0x4
  const val TYPE_PUSH_PROMISE = 0x5
  const val TYPE_PING = 0x6
  const val TYPE_GOAWAY = 0x7
  const val TYPE_WINDOW_UPDATE = 0x8
  const val TYPE_CONTINUATION = 0x9

  const val FLAG_NONE = 0x0
  const val FLAG_ACK = 0x1 // Used for settings and ping.
  const val FLAG_END_STREAM = 0x1 // Used for headers and data.