app = FastAPI()

app.add_middleware(UnicornMiddleware, some_config="rainbow")
```

`app.add_middleware()` receives a middleware class as the first argument and any additional arguments to be passed to the middleware.

## Integrated middlewares

**FastAPI** includes several middlewares for common use cases, we'll see next how to use them.

/// note | "Technical Details"

			}

			if data.valid && err != nil {
				t.Errorf("Error while verifying token: %T:%v", err, err)
			}

			if !data.valid && err == nil {
				t.Errorf("Invalid token passed validation")
			}

			if data.errors != 0 {
				_, ok := err.(*jwt.ValidationError)
				if !ok {
					t.Errorf("Expected *jwt.ValidationError, but got %#v instead", err)
				}
			}
		})
	}

 *     class (such as {@link #named(String)}) return this type, so that Builder methods of more
 *     derived classes can be chained onto them without casting.
 * @param <G> The type of the generator to be passed to testers in the generated test suite. An
 *     instance of G should somehow provide an instance of the class under test, plus any other
 *     information required to parameterize the test.
 * @see FeatureSpecificTestSuiteBuilder

   * has consumed the entire input and they are ready to output a {@code HashCode}. The order of the
   * hashers are the same order as the functions given to the constructor.
   */
  // this could be cleaner if it passed HashCode[], but that would create yet another array...
  /* protected */ abstract HashCode makeHash(Hasher[] hashers);

  @Override
  public Hasher newHasher() {
    Hasher[] hashers = new Hasher[functions.length];

		u := Err{
			msg:    msg,
			action: action,
			hint:   hint,
		}
		if err != nil {
			u.detail = err.Error()
		}
		return u
	}
}

// ErrorToErr inspects the passed error and transforms it
// to the appropriate UI error.
func ErrorToErr(err error) Err {
	if err == nil {
		return Err{}
	}

	// If this is already a Err, do nothing
	if e, ok := err.(Err); ok {

  @CheckForNull transient volatile Cell[] cells;

  /**
   * Base value, used mainly when there is no contention, but also as a fallback during table
   * initialization races. Updated via CAS.
   */
  transient volatile long base;

  /** Spinlock (locked via CAS) used when resizing and/or creating Cells. */
  transient volatile int busy;

  /** Package-private default constructor */

			w.Write([]byte(http.ErrServerClosed.Error()))
			return
		}

		atomic.AddInt32(&srv.requestCount, 1)
		defer atomic.AddInt32(&srv.requestCount, -1)

		// Handle request using passed handler.
		handler.ServeHTTP(w, r)
	})

	srv.listenerMutex.Lock()
	srv.Handler = wrappedHandler
	srv.listener = listener
	srv.listenerMutex.Unlock()

	var l net.Listener = listener

        .isEqualTo(InetAddresses.forString("0.0.0.0"));

    // test compat address (should be hashed)
    assertThat(InetAddresses.getCoercedIPv4Address(InetAddresses.forString("::1.2.3.4")))
        .isNotEqualTo(InetAddresses.forString("1.2.3.4"));

    // test 6to4 address (should be hashed)
    assertThat(InetAddresses.getCoercedIPv4Address(InetAddresses.forString("2002:0102:0304::1")))

				}
			}
		}
		traceLevel++
		// Read stack trace information from PC
		pc, file, lineNumber, ok = runtime.Caller(traceLevel)
	}
	return trace
}

// HashString - return the highway hash of the passed string
func HashString(input string) string {
	hh, _ := highwayhash.New(magicHighwayHash256Key)
	hh.Write([]byte(input))
	return hex.EncodeToString(hh.Sum(nil))
}

   * will be returned as the proxied method's return value.
   *
   * <p>Unlike {@link #invoke}, {@code args} will never be null. When the method has no parameter,
   * an empty array is passed in.
   */
  @CheckForNull
  protected abstract Object handleInvocation(Object proxy, Method method, @Nullable Object[] args)
      throws Throwable;

  /**