code: func (h *ResponseHeader) Peek(key string) []byte {
  	k := getHeaderKeyBytes(&h.bufKV, key, h.disableNormalizing)
  	return h.peek(k)
  }
docs: // Peek returns header value for the given key.
  //
  // Returned value is valid until the next call to ResponseHeader.
  // Do not store references to returned value. Make copies instead.