FLAGS[FLAG_PADDED] = "PADDED"
    for (prefixFlag in prefixFlags) {
      FLAGS[prefixFlag or FLAG_PADDED] = FLAGS[prefixFlag] + "|PADDED"
    }

    FLAGS[FLAG_END_HEADERS] = "END_HEADERS" // Same as END_PUSH_PROMISE.
    FLAGS[FLAG_PRIORITY] = "PRIORITY" // Same as FLAG_COMPRESSED.
    FLAGS[FLAG_END_HEADERS or FLAG_PRIORITY] = "END_HEADERS|PRIORITY" // Only valid on HEADERS.