} else {
        // if our write lost the race, it must have lost to a nonzero value, so we can stop
        return countMap.putIfAbsent(element, new AtomicInteger(newCount)) == null;
      }
    }
    int oldValue = existingCounter.get();
    if (oldValue == expectedOldCount) {
      if (oldValue == 0) {
        if (newCount == 0) {
          // Just observed a 0; try to remove the entry to clean up the map

```Python hl_lines="2"
@app.get('/')
def results():
    results = some_library()
    return results
```

---

If your application (somehow) doesn't have to communicate with anything else and wait for it to respond, use `async def`.

---

If you just don't know, use normal `def`.

---

**FastAPI** will create the object of type `BackgroundTasks` for you and pass it as that parameter.

## Create a task function

Create a function to be run as the background task.

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

# Security

There are many ways to handle security, authentication and authorization.

And it normally is a complex and "difficult" topic.

In many frameworks and systems just handling security and authentication takes a big amount of effort and code (in many cases it can be 50% or more of all the code written).

            }
            bufferIndex += this.byteCount;
        }

        /*
         * if there is an andx and it itself is an andx then just recur by
         * calling this method for it. otherwise just read it's parameter words
         * and bytes as usual. Note how we can't just call andx.readWireFormat
         * because there's no header.
         */

        if ( this.errorCode != 0 || this.andxCommand == (byte) 0xFF ) {

/// info

The `app.webhooks` object is actually just an `APIRouter`, the same type you would use when structuring your app with multiple files.

///

            copySpec.rename(s -> destinationFile.getName());

            // TODO: Maybe this could be simplified by not using the copy infrastructure and just
            // calling the FilterReader ourselves.  We're just taking one file and turning it into another.

            // The order here is important! tokens are inserted by the transformer
            Map<String, Object> parameters = new HashMap<>();

We can use **OAuth2** to build that with **FastAPI**.

But let's save you the time of reading the full long specification just to find those little pieces of information you need.

Let's use the tools provided by **FastAPI** to handle security.

## How it looks

Let's first just use the code and see how it works, and then we'll come back to understand what's happening.

## Create `main.py`

**FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette.

///

## Returning a custom `Response`

// just nice to know that it compiles.
void* create(TF_OpKernelConstruction* ctx) {
  TF_DataType type;
  TF_Status* s = TF_NewStatus();
  TF_OpKernelConstruction_GetAttrType(ctx, "foobar", &type, s);
  TF_DeleteStatus(s);
  return NULL;
}

// A compute function. This will never actually get called in this test, it's
// just nice to know that it compiles.