opts := ObjectOptions{
			UserDefined: map[string]string{
				xhttp.IfMatch: "wrong-etag-12345",
			},
			HasIfMatch: true,
			CheckPrecondFn: func(oi ObjectInfo) bool {
				// Precondition fails if ETags don't match
				return oi.ETag != "wrong-etag-12345"
			},
		}

		_, err := obj.NewMultipartUpload(ctx, bucket, object, opts)
		if !isErrReadQuorum(err) {
			t.Logf("Got error (as expected): %v", err)

	}

	var checksumCombined []byte

	// However, in case of encryption, the persisted part ETags don't match
	// what we have sent to the client during PutObjectPart. The reason is
	// that ETags are encrypted. Hence, the client will send a list of complete
	// part ETags of which may not match the ETag of any part. For example
	//   ETag (client):          30902184f4e62dd8f98f0aaff810c626

* `filename` - Se for definido, é incluído no cabeçalho `Content-Disposition`.

Respostas de Arquivos incluem o tamanho do arquivo, data da última modificação e ETags apropriados, nos cabeçalhos `Content-Length`, `Last-Modified` e `ETag`, respectivamente.

{* ../../docs_src/custom_response/tutorial009_py39.py hl[2,10] *}

Você também pode usar o parâmetro `response_class`: