Import `BaseSettings` from Pydantic and create a sub-class, very much like with a Pydantic model.

The same way as with Pydantic models, you declare class attributes with type annotations, and possibly default values.

You can use all the same validation features and tools you use for Pydantic models, like different data types and additional validations with `Field()`.

### Multiple Applications { #multiple-applications }

In the same server (or servers), there could be **multiple applications**, for example, other API programs or a database.

Only one process can be handling the specific IP and port (the TLS Termination Proxy in our example) but the other applications/processes can be running on the server(s) too, as long as they don't try to use the same **combination of public IP and port**.

  }

  /**
   * Returns an immutable bimap containing the given entries. The returned bimap iterates over
   * entries in the same order as the original iterable.
   *
   * @throws IllegalArgumentException if two keys have the same value or two values have the same
   *     key
   * @throws NullPointerException if any key, value, or entry is null
   * @since 19.0
   */

    }
  ]
}
```

because the path parameter `item_id` had a value of `"foo"`, which is not an `int`.

The same error would appear if you provided a `float` instead of an `int`, as in: [http://127.0.0.1:8000/items/4.2](http://127.0.0.1:8000/items/4.2)

/// check

So, with the same Python type declaration, **FastAPI** gives you data validation.

They are just a convenience, they hold the same number, but that way you can use the editor's autocomplete to find them:

<img src="/img/tutorial/response-status-code/image02.png">

/// note | Technical Details

You could also use `from starlette import status`.

@GwtCompatible
@SuppressWarnings("rawtypes") // allow ungenerified Comparable types
public abstract class ContiguousSet<C extends Comparable> extends ImmutableSortedSet<C> {
  /**
   * Returns a {@code ContiguousSet} containing the same values in the given domain {@linkplain
   * Range#contains contained} by the range.
   *
   * @throws IllegalArgumentException if neither range nor the domain has a lower bound, or if
   *     neither has an upper bound

* **Machine Learning**: it normally requires lots of "matrix" and "vector" multiplications. Think of a huge spreadsheet with numbers and multiplying all of them together at the same time.

import junit.framework.TestCase;

/**
 * Test cases for {@code EventBus} that must not be in the same package.
 *
 * @author Louis Wasserman
 */
public class OutsideEventBusTest extends TestCase {

  /*
   * If you do this test from common.eventbus.EventBusTest, it doesn't actually test the behavior.
   * That is, even if exactly the same method works from inside the common.eventbus package tests,
   * it can fail here.
   */

@GwtCompatible
@SuppressWarnings("rawtypes") // allow ungenerified Comparable types
public abstract class ContiguousSet<C extends Comparable> extends ImmutableSortedSet<C> {
  /**
   * Returns a {@code ContiguousSet} containing the same values in the given domain {@linkplain
   * Range#contains contained} by the range.
   *
   * @throws IllegalArgumentException if neither range nor the domain has a lower bound, or if
   *     neither has an upper bound

## Example Attack { #example-attack }

Imagine you build a way to run a local AI agent.

It provides an API at

```
http://localhost:8000/v1/agents/multivac
```

There's also a frontend at

```
http://localhost:8000
```

/// tip

Note that both have the same host.

///