code: func (h *ResponseHeader) AddBytesKV(key, value []byte) {
  	h.Add(b2s(key), b2s(value))
  }
docs: // AddBytesKV adds the given 'key: value' header.
  //
  // Multiple headers with the same key may be added with this function.
  // Use SetBytesKV for setting a single header for the given key.