## Technical Details { #technical-details }

The class `BackgroundTasks` comes directly from <a href="https://www.starlette.dev/background/" class="external-link" target="_blank">`starlette.background`</a>.

///

### Avoid name collisions { #avoid-name-collisions }

We are importing the submodule `items` directly, instead of importing just its variable `router`.

This is because we also have another variable named `router` in the submodule `users`.

If we had imported one after the other, like:

```Python

import org.junit.Ignore;

/**
 * Tests for {@code Multiset.equals} and {@code Multiset.hashCode}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")

You can use the `StaticFiles` class to serve static files, like JavaScript, CSS, images, etc.

Read more about it in the [FastAPI docs for Static Files](https://fastapi.tiangolo.com/tutorial/static-files/).

You can import it directly from `fastapi.staticfiles`:

```python
from fastapi.staticfiles import StaticFiles
```

import java.util.Queue;
import org.junit.Ignore;

/**
 * Base class for queue collection tests.
 *
 * @author Jared Levy
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")

import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#putIfAbsent}. Can't be invoked directly; please see
 * {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

     * on his discretion, e.g. via the {@code -Dkey=value} parameter on the command line.
     *
     * @return The user properties, never {@code null}.
     */
    Properties getUserProperties();

    /**
     * Sets the user properties to use for interpolation. The user properties have been configured directly by the user

/**
 * A generic JUnit test which tests {@code putAll} operations on a map. Can't be invoked directly;
 * please see {@link com.google.common.collect.testing.MapTestSuiteBuilder}.
 *
 * @author Chris Povirk
 * @author Kevin Bourrillion
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code remove(int)} operations on a list. Can't be invoked
 * directly; please see {@link com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@link Map#replace(Object, Object)}. Can't be invoked directly;
 * please see {@link com.google.common.collect.testing.ConcurrentMapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.