│   ├── main.py
│   └── test_main.py
```

Let's say that now the file `main.py` with your **FastAPI** app has some other **path operations**.

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

//// tab | Python 3.10+

```Python
{!> ../../docs_src/app_testing/app_b_an_py310/main.py!}
```

func (j JSON) Value() (driver.Value, error) {
	if len(j) == 0 {
		return nil, nil
	}
	return json.RawMessage(j).MarshalJSON()
}

type ExampleStruct struct {
	Name string
	Val  string
}

func (s ExampleStruct) Value() (driver.Value, error) {
	return json.Marshal(s)
}

func format(v []byte, escaper string) string {
	return escaper + strings.ReplaceAll(string(v), escaper, escaper+escaper) + escaper
}

    final Queue<Runnable> tasks = new ArrayDeque<>();

    @Override
    public void execute(Runnable command) {
      tasks.add(command);
    }

    boolean hasNext() {
      return !tasks.isEmpty();
    }

    void runNext() {
      assertTrue("expected at least one task to run", hasNext());
      tasks.remove().run();
    }

    void runAll() {
      while (hasNext()) {

  }

  absl::optional<std::vector<int64_t>> make_shape(
      std::vector<int64_t>&& dims) const {
    return absl::make_optional(dims);
  }

  absl::optional<std::vector<int64_t>> unknown_shape() const {
    return absl::nullopt;
  }

  static constexpr int64_t kUnknownDim =
      shape_inference::InferenceContext::kUnknownDim;
  TF_Status* status_;

          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);
            Thread.sleep(10);
            ticker.advance(1L);
            return null;
          }
        });

    assertEquals(numberOfThreads * 2, ticker.read());
  }

  @GwtIncompatible // concurrency

  public void testConcurrentAutoIncrementStep() throws Exception {

  @CanIgnoreReturnValue
  public RelationshipTester<T> addRelatedGroup(Iterable<? extends T> group) {
    groups.add(ImmutableList.copyOf(group));
    return this;
  }

  public void test() {
    for (int groupNumber = 0; groupNumber < groups.size(); groupNumber++) {
      ImmutableList<T> group = groups.get(groupNumber);

    val out = Buffer()
    Hpack.Writer(out = out).writeHeaders(sentHeaders)
    return out
  }

  private fun sendHeaderFrames(
    outFinished: Boolean,
    headers: List<Header>,
  ): Buffer {
    val out = Buffer()
    Http2Writer(out, true).headers(outFinished, expectedStreamId, headers)
    return out
  }

  private fun sendPushPromiseFrames(
    streamId: Int,

    @Override
    public boolean apply(@Nullable Integer i) {
      return (i.intValue() & 1) == 1;
    }

    @Override
    public int hashCode() {
      return 0x150dd;
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      return obj instanceof IsOdd;
    }

    @Override
    public String toString() {
      return "IsOdd";
    }
  }

  /**

    Entry<String, Integer> entry =
        new AbstractMapEntry<String, Integer>() {
          @Override
          public String getKey() {
            return holder.string;
          }

          @Override
          public Integer getValue() {
            return 1;
          }
        };

    builder.put(entry);
    holder.string = "two";
    assertMapEquals(builder.build(), "one", 1);
  }

    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):
    return {"item_name": item.name, "item_id": item_id}
```