You could still use most of the features in **FastAPI** with the knowledge from the main [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank}.

    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked(1);
      cache.getUnchecked(2);

      Set<Object> keys = cache.asMap().keySet();
      // We don't know whether these are still in the cache, so we can't assert on the return
      // values of these removes, but the cache should be empty after the removes, regardless.
      keys.remove(1);
      keys.remove(2);

    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked(1);
      cache.getUnchecked(2);

      Set<Object> keys = cache.asMap().keySet();
      // We don't know whether these are still in the cache, so we can't assert on the return
      // values of these removes, but the cache should be empty after the removes, regardless.
      keys.remove(1);
      keys.remove(2);

The query parameter `q` is of type `str | None`, that means that it's of type `str` but could also be `None`, and indeed, the default value is `None`, so FastAPI will know it's not required.

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

Having `str | None` will allow your editor to give you better support and detect errors.

///

import okio.BufferedSink
import okio.GzipSink
import okio.buffer

internal class GzipRequestBody(
  val delegate: RequestBody,
) : RequestBody() {
  override fun contentType() = delegate.contentType()

  // We don't know the compressed length in advance!
  override fun contentLength() = -1L

  override fun writeTo(sink: BufferedSink) {
    GzipSink(sink).buffer().use(delegate::writeTo)
  }

	typedef enum {
		SID_NAME_USE_NONE = 0, /* NOTUSED */
		SID_NAME_USER     = 1, /* user */
		SID_NAME_DOM_GRP  = 2, /* domain group */
		SID_NAME_DOMAIN   = 3, /* domain: don't know what this is */
		SID_NAME_ALIAS    = 4, /* local group */
		SID_NAME_WKN_GRP  = 5, /* well-known group */
		SID_NAME_DELETED  = 6, /* deleted account: needed for c2 rating */
		SID_NAME_INVALID  = 7, /* invalid account */
		SID_NAME_UNKNOWN  = 8  /* oops. */
	} LsarSidType;

	typedef enum {
		SID_NAME_USE_NONE = 0, /* NOTUSED */
		SID_NAME_USER     = 1, /* user */
		SID_NAME_DOM_GRP  = 2, /* domain group */
		SID_NAME_DOMAIN   = 3, /* domain: don't know what this is */
		SID_NAME_ALIAS    = 4, /* local group */
		SID_NAME_WKN_GRP  = 5, /* well-known group */
		SID_NAME_DELETED  = 6, /* deleted account: needed for c2 rating */
		SID_NAME_INVALID  = 7, /* invalid account */
		SID_NAME_UNKNOWN  = 8  /* oops. */
	} LsarSidType;

# Environment Variables { #environment-variables }

/// tip

If you already know what "environment variables" are and how to use them, feel free to skip this.

///

An environment variable (also known as "**env var**") is a variable that lives **outside** of the Python code, in the **operating system**, and could be read by your Python code (or by other programs as well).

  <!-- Hack to keep collect from hiding collect.testing supersource: -->
  <exclude name="**/testing/**"/>
</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see

You can also declare a body as a `dict` with keys of some type and values of some other type.

This way, you don't have to know beforehand what the valid field/attribute names are (as would be the case with Pydantic models).

This would be useful if you want to receive keys that you don't already know.

---

Another useful case is when you want to have keys of another type (e.g., `int`).