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`).

When you mount a sub-application as described above, FastAPI will take care of communicating the mount path for the sub-application using a mechanism from the ASGI specification called a `root_path`.

That way, the sub-application will know to use that path prefix for the docs UI.

And the sub-application could also have its own mounted sub-applications and everything would work correctly, because FastAPI handles all these `root_path`s automatically.

# -------
*.classpath
*.project
*.settings
/bin
/subprojects/*/bin
atlassian-ide-plugin.xml
.metadata/

# NetBeans
# --------
.nb-gradle
.nb-gradle-properties

# Vim
# ---
*.sw[nop]

# Emacs
# -----
*~
\#*\#
.\#*

# Textmate
# --------
.textmate

# Sublime Text
# ------------
*.sublime-*

# jEnv
# ----
.java-version

# macOS
# ----

    }

    try {
      if (method == NEXT_METHOD
          && targetException == null
          && knownOrder == KnownOrder.UNKNOWN_ORDER) {
        /*
         * We already know the iterator is an Iterator<E>, and now we know that
         * we called next(), so the returned element must be of type E.
         */
        @SuppressWarnings("unchecked")
        E targetReturnValueFromNext = (E) targetReturnValue;

      return new RequestBody() {
        @Override public MediaType contentType() {
          return body.contentType();
        }

        @Override public long contentLength() {
          return -1; // We don't know the compressed length in advance!
        }

        @Override public void writeTo(BufferedSink sink) throws IOException {
          BufferedSink gzipSink = Okio.buffer(new GzipSink(sink));
          body.writeTo(gzipSink);

    }

    public void test_getText_null() {
        try {
            msWordExtractor.getText(null, null);
            fail();
        } catch (final CrawlerSystemException e) {
            // NOP
        }
    }

    }

    public void test_getText_null() {
        try {
            msExcelExtractor.getText(null, null);
            fail();
        } catch (final CrawlerSystemException e) {
            // NOP
        }
    }

    }

    public void test_getText_null() {
        try {
            msPowerPointExtractor.getText(null, null);
            fail();
        } catch (final CrawlerSystemException e) {
            // NOP
        }
    }

/// note

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

The `str | None` (Python 3.10+) or `Union` in `Union[str, None]` (Python 3.8+) is not used by FastAPI to determine that the value is not required, it will know it's not required because it has a default value of `= None`.

// It returns free space available to the user (including quota limitations)
//
// https://msdn.microsoft.com/en-us/library/windows/desktop/aa364937(v=vs.85).aspx
func GetInfo(path string, _ bool) (info Info, err error) {
	// Stat to know if the path exists.
	if _, err = os.Stat(path); err != nil {
		return Info{}, err
	}

	lpFreeBytesAvailable := int64(0)
	lpTotalNumberOfBytes := int64(0)
	lpTotalNumberOfFreeBytes := int64(0)