But if you need to access variables and objects from the same **FastAPI** app, or you need to perform small background tasks (like sending an email notification), you can simply just use `BackgroundTasks`.

## Recap { #recap }

// only one of Prefix, And and Tag should be present in the output.
func (f Filter) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	if err := e.EncodeToken(start); err != nil {
		return err
	}

	switch {
	case !f.And.isEmpty():
		if err := e.EncodeElement(f.And, xml.StartElement{Name: xml.Name{Local: "And"}}); err != nil {
			return err
		}
	case !f.Tag.IsEmpty():

from OkHttp 4.x:

**OkHttp is now packaged as separate JVM and Android artifacts.** This allows us to offer
platform-specific features and optimizations. If your build system handles [Gradle module metadata],
this change should be automatic.

**MockWebServer has a new coordinate and package name.** We didn’t like that our old artifact

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header` { #import-header }

First import `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

    // and friends, and that we will eventually expect to see garbage-collected. The assumption
    // is that the ClassLoader of this test is a URLClassLoader, and that it loads FRQ itself
    // rather than delegating to a parent ClassLoader. If this assumption is violated the test will
    // fail and will need to be rewritten.

    Class<?> frqC = FinalizableReferenceQueue.class;

    val flags = buf.readShort().toInt() and 0xffff
    require(flags shr 15 != 0) { "not a response" }

    val responseCode = flags and 0xf

    if (responseCode == NXDOMAIN) {
      throw UnknownHostException("$hostname: NXDOMAIN")
    } else if (responseCode == SERVFAIL) {
      throw UnknownHostException("$hostname: SERVFAIL")
    }

    val questionCount = buf.readShort().toInt() and 0xffff

    @MethodSource("intErrorCodes")
    @DisplayName("int ctor: sets message and NT status as expected")
    void intConstructor_populatesMessageAndStatus(int errCode, int expectedStatus) {
        // Arrange & Act: create exception with error code
        SmbAuthException ex = new SmbAuthException(errCode);

        // Assert: type, message derived from code, status mapping, and no cause
        assertNotNull(ex);

This notification target supports two formats: _namespace_ and _access_.

Make sure you create a [virtual environment](../virtual-environments.md), activate it, and then install it, for example:

```console
$ pip install python-multipart
```

This is because uploaded files are sent as "form data".

///

## Import `File` { #import-file }

Import `File` and `UploadFile` from `fastapi`:

{* ../../docs_src/request_files/tutorial001_an_py310.py hl[3] *}

#       options in "$@", and eventually passing that to Java.
#
#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
#       see the in-line comments for details.
#
#       There are tweaks for specific operating systems such as AIX, CygWin,
#       Darwin, MinGW, and NonStop.
#
#   (3) This script is generated from the Groovy template