code: func (resp *Response) SetBodyStreamWriter(sw StreamWriter) {
  	sr := NewStreamReader(sw)
  	resp.SetBodyStream(sr, -1)
  }
docs: // SetBodyStreamWriter registers the given sw for populating response body.
  //
  // This function may be used in the following cases:
  //
  //     * if response body is too big (more than 10MB).
  //     * if response body is streamed from slow external sources.
  //     * if response body must be streamed to the client in chunks
  //     (aka `http server push` or `chunked transfer-encoding`).
  //
  // See also SetBodyStream.