///

In the docs UI at <a href="http://127.0.0.1:9999/api/v1/docs" class="external-link" target="_blank">http://127.0.0.1:9999/api/v1/docs</a> it would look like:

<img src="/img/tutorial/behind-a-proxy/image03.png">

/// tip

The docs UI will interact with the server that you select.

///

    protected WebConfigService webConfigService;

    // ===================================================================================
    //                                                                               Hook
    //                                                                              ======
    @Override
    protected void setupHtmlData(final ActionRuntime runtime) {
        super.setupHtmlData(runtime);

      } else if (c1 <= Character.MAX_HIGH_SURROGATE) {
        // If the high surrogate was the last character, return its inverse
        if (index == end) {
          return -c1;
        }
        // Otherwise look for the low surrogate following it
        char c2 = seq.charAt(index);
        if (Character.isLowSurrogate(c2)) {
          return Character.toCodePoint(c1, c2);
        }
        throw new IllegalArgumentException(

The same example from above, returning an `HTMLResponse`, could look like:

{* ../../docs_src/custom_response/tutorial003.py hl[2,7,19] *}

/// warning

      } else if (c1 <= Character.MAX_HIGH_SURROGATE) {
        // If the high surrogate was the last character, return its inverse
        if (index == end) {
          return -c1;
        }
        // Otherwise look for the low surrogate following it
        char c2 = seq.charAt(index);
        if (Character.isLowSurrogate(c2)) {
          return Character.toCodePoint(c1, c2);
        }
        throw new IllegalArgumentException(

   * GWT SortedMap implementation that we delegate to throws
   * NullPointerException if the comparator does. Since our construction
   * methods ensure that null is never present in the map, it's OK for the
   * comparator to look for it wherever it wants.
   *
   * Note that we do NOT touch the comparator returned by comparator(), which
   * should be identical to the one the user passed in. We touch only the

The section:

```Python
from .routers import items, users
```

means:

* Starting in the same package that this module (the file `app/main.py`) lives in (the directory `app/`)...
* look for the subpackage `routers` (the directory at `app/routers/`)...
* and from it, import the submodule `items` (the file at `app/routers/items.py`) and `users` (the file at `app/routers/users.py`)...

You would of course use the same ideas you read in [About FastAPI versions](versions.md){.internal-link target=_blank} to set the ranges of versions.

For example, your `requirements.txt` could look like:

```
fastapi[standard]>=0.113.0,<0.114.0
pydantic>=2.7.0,<3.0.0
```

And you would normally install those package dependencies with `pip`, for example:

<div class="termy">

```console

# WARNING: THESE OPTIONS WONT WORK IF YOU DO NOT HAVE PROPER AUTHENTICATION AND PERMISSIONS

# Use --config=tf_public_cache to try and use the TensorFlow public build cache
# to build TensorFlow. Look at ci/official/envs to find which types of jobs
# push to the cache.  For macOS, use --config=tf_public_macos_cache

    @Override
    public String toString() {
      return getKey() + "=" + getValue();
    }
  }

  // TODO(fry): Separate logic for consistency between emul and nonemul implementation.
  // TODO(fry): Look into Maps.KeySet and Maps.Values, which can ideally be reused here but are
  // currently only package visible.
  abstract class AbstractCacheSet<T> extends AbstractSet<T> {
    final ConcurrentMap<?, ?> map;