```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

Using `Optional[str]` instead of just `str` will let the editor help you detect errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

- github.com/docker/docker: [v20.10.18+incompatible → v20.10.21+incompatible](https://github.com/docker/docker/compare/v20.10.18...v20.10.21)
- github.com/go-errors/errors: [v1.0.1 → v1.4.2](https://github.com/go-errors/errors/compare/v1.0.1...v1.4.2)
- github.com/go-openapi/jsonpointer: [v0.19.5 → v0.19.6](https://github.com/go-openapi/jsonpointer/compare/v0.19.5...v0.19.6)

//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package dsync

import (
	"context"
	"errors"
	"math/rand"
	"sort"
	"strconv"
	"sync"
	"time"

	xioutil "github.com/minio/minio/internal/ioutil"
	"github.com/minio/minio/internal/mcontext"
	"github.com/minio/pkg/v3/console"

│   └── test_main.py
```

Let's say that now the file `main.py` with your **FastAPI** app has some other **path operations**.

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

//// tab | Python 3.10+

```Python
{!> ../../docs_src/app_testing/app_b_an_py310/main.py!}
```

////

            }

            slf4jLogger.error("");

            if (!cliRequest.showErrors) {
                slf4jLogger.error(
                        "To see the full stack trace of the errors, re-run Maven with the '{}' switch",
                        MessageUtils.builder().strong("-e"));
            }
            if (!slf4jLogger.isDebugEnabled()) {
                slf4jLogger.error(

			addr := obj.Addr{}
			parser.operand(&addr)
		})

		switch {
		case err == nil:
			t.Errorf("fail at %s: got no errors; expected %s\n", test.input, test.error)
		case !strings.Contains(err.Error(), test.error):
			t.Errorf("fail at %s: got %s; expected %s", test.input, err, test.error)
		}
	}
}

func testOperandParser(t *testing.T, parser *Parser, tests []operandTest) {
	for _, test := range tests {

// Code generated by "stringer -type=APIErrorCode -trimprefix=Err api-errors.go"; DO NOT EDIT.

package cmd

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[ErrNone-0]
	_ = x[ErrAccessDenied-1]
	_ = x[ErrBadDigest-2]
	_ = x[ErrEntityTooSmall-3]
	_ = x[ErrEntityTooLarge-4]

     * best we can do (since logging may overflow the stack) is to let the error propagate. Because
     * it is an Error, it won't be caught and logged by AbstractFuture.executeListener. Instead, it
     * can propagate through many layers of AbstractTransformFuture up to the root call to set().
     *
     * https://github.com/google/guava/issues/2254
     *
     * Other kinds of Errors are possible:
     *

    - tutorial/response-status-code.md
    - tutorial/request-forms.md
    - tutorial/request-form-models.md
    - tutorial/request-files.md
    - tutorial/request-forms-and-files.md
    - tutorial/handling-errors.md
    - tutorial/path-operation-configuration.md
    - tutorial/encoder.md
    - tutorial/body-updates.md
    - Dependencies:
      - tutorial/dependencies/index.md

	if !ok && tx.DryRun {
		db.Logger.Error(tx.Statement.Context, ErrDryRunModeUnsupported.Error())
	}
	return row
}

func (db *DB) Rows() (*sql.Rows, error) {
	tx := db.getInstance().Set("rows", true)
	tx = tx.callbacks.Row().Execute(tx)
	rows, ok := tx.Statement.Dest.(*sql.Rows)
	if !ok && tx.DryRun && tx.Error == nil {
		tx.Error = ErrDryRunModeUnsupported
	}
	return rows, tx.Error
}