```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009_py39.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.

		}
		if errorResponse.Resource != testCase.errorResponse.Resource {
			t.Errorf("Test %d: %s: Expected the error resource to be `%s`, but instead found `%s`", i+1, instanceType, testCase.errorResponse.Resource, errorResponse.Resource)
		}
		if errorResponse.Message != testCase.errorResponse.Message {

			usage = madmin.Usage{Size: dataUsageInfo.ObjectsTotalSize}
		} else {
			buckets = madmin.Buckets{Error: err.Error()}
			objects = madmin.Objects{Error: err.Error()}
			deleteMarkers = madmin.DeleteMarkers{Error: err.Error()}
			usage = madmin.Usage{Error: err.Error()}
		}

		// Fetching the backend information
		backendInfo := objectAPI.BackendInfo()

			if testCase.expectedError.Error() != actualErr.Error() {
				t.Errorf("Test %d: %s: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead.", i+1,
					instanceType, testCase.expectedError.Error(), actualErr.Error())
			}
		}
		// Test passes as expected, but the output values are verified for correctness here.
		if actualErr == nil && testCase.shouldPass {

]

[tool.coverage.report]
show_missing = true
sort = "-Cover"

[tool.coverage.html]
show_contexts = true

[tool.ruff.lint]
select = [
    "E",  # pycodestyle errors
    "W",  # pycodestyle warnings
    "F",  # pyflakes
    "I",  # isort
    "B",  # flake8-bugbear
    "C4",  # flake8-comprehensions
    "UP",  # pyupgrade
]
ignore = [

			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 {

### Errores Pequeños Manejados Automáticamente { #small-errors-automatically-handled }

Al construir APIs web con FastAPI, si hay un error en nuestro código, FastAPI normalmente lo contiene al request único que desencadenó el error. 🛡

// 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]

"modulus must be > 1" _, err := NewModulus([]byte{}) if err == nil || err.Error() != expected { t.Errorf("NewModulus(0) got %q, want %q", err, expected) } _, err = NewModulus([]byte{0}) if err == nil || err.Error() != expected { t.Errorf("NewModulus(0) got %q, want %q", err, expected) } _, err = NewModulus([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}) if err == nil || err.Error() != expected { t.Errorf("NewModulus(0) got %q, want %q", err, expected) } _, err = NewModulus([]byte{1})...

     *
     * @param paramMap the data store parameters
     * @param dataMap the document data to store
     * @throws DataStoreException if required fields are missing or other errors occur
     */
    @Override
    public void store(final DataStoreParams paramMap, final Map<String, Object> dataMap) {
        final SystemHelper systemHelper = ComponentUtil.getSystemHelper();