You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

## Pin your `fastapi` version { #pin-your-fastapi-version }

Just functions that look the same as the *path operation functions*.

But still, it is very powerful, and allows you to declare arbitrarily deeply nested dependency "graphs" (trees).

/// tip

All this might not seem as useful with these simple examples.

But you will see how useful it is in the chapters about **security**.

And you will also see the amounts of code it will save you.

<img src="/img/tutorial/path-operation-configuration/image01.png">

### Tags with Enums { #tags-with-enums }

If you have a big application, you might end up accumulating **several tags**, and you would want to make sure you always use the **same tag** for related *path operations*.

In these cases, it could make sense to store the tags in an `Enum`.

}

// JoinNestedRelationNames nested relationships like `Manager__Company`
func JoinNestedRelationNames(relationNames []string) string {
	return strings.Join(relationNames, nestedRelationSplit)
}

// RTrimSlice Right trims the given slice by given length
func RTrimSlice[T any](v []T, trimLen int) []T {
	if trimLen >= len(v) { // trimLen greater than slice len means fully sliced
		return v[:0]
	}

modified by someone else and passed on, the recipients should know
that what they have is not the original version, so that the original
author's reputation will not be affected by problems that might be
introduced by others.

  Finally, software patents pose a constant threat to the existence of
any free program.  We wish to make sure that a company cannot
effectively restrict the users of a free program by obtaining a

    Function<Float, Boolean> c1 = Functions.compose(Functions.compose(h, g), f);
    Function<Float, Boolean> c2 = Functions.compose(h, Functions.compose(g, f));

    // Might be nice (eventually) to have:
    //     assertEquals(c1, c2);

    // But for now, settle for this:
    assertEquals(c1.hashCode(), c2.hashCode());

    assertEquals(c1.apply(1.0f), c2.apply(1.0f));

 *
 * <p>A min-max priority queue can be configured with a maximum size. If so, each time the size of
 * the queue exceeds that value, the queue automatically removes its greatest element according to
 * its comparator (which might be the element that was just added). This is different from
 * conventional bounded queues, which either block or reject new elements when full.
 *
 * <p>This implementation is based on the <a

          Arrays.sort(sortedKs, comparator);
          Object[] sortedValues = new Object[size];

          // We might, somehow, be able to reorder values in-place.  But it doesn't seem like
          // there's a way around creating the separate sortedKeys array, and if we're allocating
          // one array of size n, we might as well allocate two -- to say nothing of the allocation
          // done in Arrays.sort.

      # - 25 for running Javadoc and javac (to help people who build Guava locally and might not use a recent JDK to run Maven)
      - name: 'Set up JDKs'
        uses: actions/setup-java@dded0888837ed1f317902acf8a20df0ad188d165 # v5.0.0
        with:
          java-version: |
            ${{ matrix.java }}

import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests that all package-private {@code writeReplace} methods are overridden in any existing
 * subclasses. Without such overrides, optimizers might put a {@code writeReplace}-containing class
 * and its subclass in different packages, causing the serialization system to fail to invoke {@code