Because it's a Python exception, you don't `return` it, you `raise` it.

This also means that if you are inside a utility function that you are calling inside of your *path operation function*, and you raise the `HTTPException` from inside of that utility function, it won't run the rest of the code in the *path operation function*, it will terminate that request right away and send the HTTP error from the `HTTPException` to the client.

   *
   * @return the composition of the provided function and predicate
   */
  public static <A extends @Nullable Object, B extends @Nullable Object> Predicate<A> compose(
      Predicate<B> predicate, Function<A, ? extends B> function) {
    return new CompositionPredicate<>(predicate, function);
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the {@code CharSequence} being tested

	dw := &DeadlineWorker{
		timeout: timeout,
	}
	return dw
}

// Run runs the given function, passing it a stopper channel. If the deadline passes before
// the function finishes executing, Run returns context.DeadlineExceeded to the caller.
// channel so that the work function can attempt to exit gracefully.
// Multiple calls to Run will run independently of each other.

但如果你確定在從路徑操作函式返回後就不會再使用該相依，你可以使用 `Depends(scope="function")`，告訴 FastAPI 應在路徑操作函式返回之後、但在回應送出之前關閉該相依。

{* ../../docs_src/dependencies/tutorial008e_an_py310.py hl[12,16] *}

`Depends()` 接受一個 `scope` 參數，可以是：

* `"function"`：在處理請求的路徑操作函式之前啟動相依，在路徑操作函式結束之後結束相依，但在回應送回用戶端之前。所以，相依函式會在路徑操作**函式**的「周圍」執行。
* `"request"`：在處理請求的路徑操作函式之前啟動相依（與使用 `"function"` 類似），但在回應送回用戶端之後才結束相依。所以，相依函式會在整個**請求**與回應循環的「周圍」執行。

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Comparator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Function;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * GWT emulation of {@link com.google.common.collect.ImmutableBiMap}.
 *
 * @author Hayward Chan
 */

 * limitations under the License.
 */

package com.google.common.collect;

import static java.util.Arrays.asList;

import com.google.common.base.Function;
import com.google.common.collect.testing.CollectionTestSuiteBuilder;
import com.google.common.collect.testing.MinimalCollection;
import com.google.common.collect.testing.TestStringCollectionGenerator;

 * limitations under the License.
 */

package com.google.common.collect;

import static java.util.Arrays.asList;

import com.google.common.base.Function;
import com.google.common.collect.testing.QueueTestSuiteBuilder;
import com.google.common.collect.testing.TestStringQueueGenerator;
import com.google.common.collect.testing.features.CollectionFeature;

In this case, we pass a dependency function `get_current_active_user` to `Security` (the same way we would do with `Depends`).

But we also pass a `list` of scopes, in this case with just one scope: `items` (it could have more).

And the dependency function `get_current_active_user` can also declare sub-dependencies, not only with `Depends` but also with `Security`. Declaring its own sub-dependency function (`get_current_user`), and more scope requirements.

    // we pad because the dummy hash function we use to test this, merely copies the input into
    // the output, so the input must be at least 32 bits, since the output has to be that long
    assertPutString(new char[] {'p', HashTestUtils.randomLowSurrogate(new Random())});
  }

  public void testPutStringWithHighSurrogate() {
    // we pad because the dummy hash function we use to test this, merely copies the input into

                function* ends, but **before** the response is sent back to the client.
                So, the dependency function will be executed **around** the *path operation
                **function***.
            * `"request"`: start the dependency before the *path operation function*
                that handles the request (similar to when using `"function"`), but end