* `fixedquery`: has the exact value `fixedquery`.
* `$`: ends there, doesn't have any more characters after `fixedquery`.

If you feel lost with all these **"regular expression"** ideas, don't worry. They are a hard topic for many people. You can still do a lot of stuff without needing regular expressions yet.

Now you know that whenever you need them you can use them in **FastAPI**.

This can be used as a quick shortcut if you have only one Pydantic model and want to remove some data from the output.

/// tip

But it is still recommended to use the ideas above, using multiple classes, instead of these parameters.

    // we try hard to make them robust in practice.  We could additionally try to add in a system
    // load timeout multiplier.  Or we could try to use a CPU time bound instead of wall clock time
    // bound.  But these ideas are harder to implement.  We do not try to detect or handle a
    // user-specified -XX:+DisableExplicitGC.
    //
    // TODO(user): Consider using
    // java/lang/management/OperatingSystemMXBean.html#getSystemLoadAverage()

        };
    try {
      Hashing.hmacMd5(badKey);
      fail();
    } catch (IllegalArgumentException expected) {
    } catch (NullPointerException toleratedOnAndroid) {
      // TODO(cpovirk): In an ideal world, we'd check here that we're running on Android.
    }
  }

  public void testEmptyInputs() throws Exception {
    String knownOutput = "8cbf764cbe2e4623d99a41354adfd390";

        // This test validates that paths which should be UNC but aren't detected due to normalization
        // still pass validation (which is the current behavior, though not ideal)

        // These paths normalize to \server\share which is NOT detected as UNC due to normalization
        String normalizedPath = noUncValidator.validatePath("\\\\\\\\server\\\\\\\\share");

{* ../../docs_src/handling_errors/tutorial006.py hl[2:5,15,21] *}

* **Ó yára láti kóòdù**: O mu iyara pọ si láti kọ àwọn ẹya tuntun kóòdù nipasẹ "Igba ìdá ọgọ́rùn-ún" (i.e. 200%) si "ọ̀ọ́dúrún ìdá ọgọ́rùn-ún" (i.e. 300%).
* **Àìtọ́ kékeré**: O n din aṣiṣe ku bi ọgbon ìdá ọgọ́rùn-ún (i.e. 40%) ti eda eniyan (oṣiṣẹ kóòdù) fa. *

    * Als je bekend bent Python types, weet je hoe je Pydantic moet gebruiken.
* Werkt goed samen met je **<abbr title=“Integrated Development Environment, vergelijkbaar met een code editor”>IDE</abbr>/<abbr title=“Een programma dat controleert op fouten in de code”>linter</abbr>/hersenen**:

You can consider this a brief OpenAPI and JSON Schema **history lesson**. 🤓

///

/// warning

These are very technical details about the standards **JSON Schema** and **OpenAPI**.

If the ideas above already work for you, that might be enough, and you probably don't need these details, feel free to skip them.

///

Before OpenAPI 3.1.0, OpenAPI used an older and modified version of **JSON Schema**.

La forma más común de hacerlo es tener un archivo `requirements.txt` con los nombres de los paquetes y sus versiones, uno por línea.

Por supuesto, usarías las mismas ideas que leíste en [Acerca de las versiones de FastAPI](versions.md){.internal-link target=_blank} para establecer los rangos de versiones.

Por ejemplo, tu `requirements.txt` podría verse así:

```