}

    /**
     * Parameterized version of testActivatedDefaultProfileBySource that demonstrates
     * cross-platform path behavior using JIMFS to simulate both Windows and Unix file systems.
     * This test shows how the path separator expectations differ between platforms.
     */
    @ParameterizedTest(name = "testActivatedDefaultProfileBySource[{0}]")
    @MethodSource("fileSystemConfigurations")

```

/// tip

If you want to learn more about HTTPS, check the guide [About HTTPS](../deployment/https.md){.internal-link target=_blank}.

///

### How Proxy Forwarded Headers Work { #how-proxy-forwarded-headers-work }

Here's a visual representation of how the **proxy** adds forwarded headers between the client and the **application server**:

```mermaid
sequenceDiagram
    participant Client

### **4.1 Spark Pi**

Test the Spark installation by running the following compute intensive example, which calculates pi by “throwing darts” at a circle. The program generates points in the unit square ((0,0) to (1,1)) and counts how many points fall within the unit circle within the square. The result approximates pi.

Request newYorkTimesRequest = new Request.Builder()
    .url("https://www.nytimes.com/")
    .build();
client.newCall(newYorkTimesRequest).enqueue(new Callback() {
  ...
});
```

Running this race over home WiFi shows the Times (`0002`) completes just slightly sooner than the Post (`0001`):

```
0001 https://www.washingtonpost.com/
0001 0.000 callStart
0002 https://www.nytimes.com/
0002 0.000 callStart
0002 0.010 dnsStart

```

In response, the self-contained JWT id_token will be returned as shown below.

```
{

   * @param buffer where to add the transferred elements
   * @param numElements the number of elements to be waited for
   * @param timeout how long to wait before giving up, in units of {@code unit}
   * @param unit a {@code TimeUnit} determining how to interpret the timeout parameter
   * @return the number of elements transferred
   * @throws InterruptedException if interrupted while waiting
   */

      codePoint.toChar() in encodeSet ||
      codePoint == '%'.code &&
      (!alreadyEncoded || strict && !isPercentEncoded(i, limit)) ||
      codePoint == '+'.code &&
      plusIsSpace
    ) {
      // Slow path: the character at i requires encoding!
      val out = Buffer()
      out.writeUtf8(this, pos, i)
      out.writeCanonicalized(
        input = this,
        pos = i,
        limit = limit,

# Tutorial - User Guide { #tutorial-user-guide }

This tutorial shows you how to use **FastAPI** with most of its features, step by step.

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference so you can come back and see exactly what you need.

## Run the code { #run-the-code }

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

You can import them from `fastapi.security`:

```python
from fastapi.security import (
    APIKeyCookie,
    APIKeyHeader,

All these dependencies, while declaring their requirements, also add parameters, validations, etc. to your *path operations*.