## Description from docstring { #description-from-docstring }

As descriptions tend to be long and cover multiple lines, you can declare the *path operation* description in the function <abbr title="a multi-line string as the first expression inside a function (not assigned to any variable) used for documentation">docstring</abbr> and **FastAPI** will read it from there.

{* ../../docs_src/path_operation_advanced_configuration/tutorial003.py hl[6] *}

## Advanced description from docstring { #advanced-description-from-docstring }

You can limit the lines used from the docstring of a *path operation function* for OpenAPI.

Adding an `\f` (an escaped "form feed" character) causes **FastAPI** to truncate the output used for OpenAPI at this point.

It is a plug-in for many frameworks (and there's a plug-in for Starlette too).

The way it works is that you write the definition of the schema using YAML format inside the docstring of each function handling a route.

And it generates OpenAPI schemas.

That's how it works in Flask, Starlette, Responder, etc.

* Add support for truncating docstrings from *path operation functions*.
    * New docs at [Advanced description from docstring](https://fastapi.tiangolo.com/advanced/path-operation-advanced-configuration/#advanced-description-from-docstring).
    * PR [#556](https://github.com/tiangolo/fastapi/pull/556) by [@svalouch](https://github.com/svalouch).

        weighting is done on linear magnitude spectra (sqrt of inputs).
    *   Change `tf.contrib.distributions` docstring examples to use `tfd` alias
        rather than `ds`, `bs`.
    *   Fix docstring typos in `tf.distributions.bijectors.Bijector`.
    *   `tf.assert_equal` no longer raises `ValueError.` It now raises
        `InvalidArgumentError,` as documented.

    }

    @Nested
    @DisplayName("toString() Tests")
    class ToStringTests {

        @Test
        @DisplayName("toString with valid data produces expected format")
        void testToStringWithValidData() {
            byte[] challenge = new byte[] { (byte) 0x01, (byte) 0x02, (byte) 0x03, (byte) 0xFF };
            UniAddress dc = mock(UniAddress.class);
            when(dc.toString()).thenReturn("SERVER123");

        short maxLength = 20;
        int pointer = 100;
        PacUnicodeString pacString = new PacUnicodeString(length, maxLength, pointer);

        // Verify that the object was created
        assertNotNull(pacString, "The PacUnicodeString object should not be null.");

        // Verify that the getters return the correct values
        assertEquals(length, pacString.getLength(), "The length should match the value provided in the constructor.");

        assertEquals(info1.toString(), info2.toString());
    }

    @Test
    @DisplayName("Test encode does not modify source object")
    void testEncodeImmutability() {
        long originalValue = 1000L;
        FileEndOfFileInformation info = new FileEndOfFileInformation(originalValue);

        // Get original toString
        String originalString = info.toString();

        // Encode

        assertEquals("VERSION_2", WitnessVersion.VERSION_2.toString());

        assertEquals("RESOURCE_CHANGE", WitnessEventType.RESOURCE_CHANGE.toString());
        assertEquals("CLIENT_MOVE", WitnessEventType.CLIENT_MOVE.toString());
        assertEquals("SHARE_MOVE", WitnessEventType.SHARE_MOVE.toString());
        assertEquals("IP_CHANGE", WitnessEventType.IP_CHANGE.toString());

            UUID uuid = new UUID(rpcUuid);

            // Act
            String result = uuid.toString();

            // Assert
            assertEquals(VALID_UUID_STRING, result.toUpperCase(), "toString() should return the correct UUID string in uppercase");
        }

        @Test
        @DisplayName("toString() should work correctly for UUID created from string")
        void testToStringFromConstructorWithString() {