All the dependencies we have seen are a fixed function or class.

But there could be cases where you want to be able to set parameters on the dependency, without having to declare many different functions or classes.

Let's imagine that we want to have a dependency that checks if the query parameter `q` contains some fixed content.

But we want to be able to parameterize that fixed content.

There have been many tools created before that have helped inspire its creation.

I have been avoiding the creation of a new framework for several years. First I tried to solve all the features covered by **FastAPI** using many different frameworks, plug-ins, and tools.

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

/**
 * Tests our AtomicHelper fallback strategy in AggregateFutureState.
 *
 * <p>On different platforms AggregateFutureState uses different strategies for its core
 * synchronization primitives. The strategies are all implemented as subtypes of AtomicHelper and

        @Override
        public CredentialsInternal renew() {
            // Returns null to represent an implementation that could not renew
            return null;
        }
    }

    // Provide different implementation behaviors to a parameterized test
    static Stream<Arguments> implementations() {
        return Stream.of(Arguments.of("returns self", (Supplier<SmbRenewableCredentials>) SelfRenewingCreds::new, true, false),

import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

/**
 * Unit tests for the {@link ConsoleIcon} enum.
 * Tests icon rendering with different terminal charsets and fallback behavior.
 */
@DisplayName("ConsoleIcon")
class ConsoleIconTest {

    @Test
    @DisplayName("should return Unicode icons when terminal supports UTF-8")

	s2, err := os.Lstat(filepath.Dir(strings.TrimSuffix(path, "/")))
	if err != nil {
		return false
	}

	// If the directory has a different device as parent, then it is a mountpoint.
	ss1, ok1 := s1.Sys().(*syscall.Stat_t)
	ss2, ok2 := s2.Sys().(*syscall.Stat_t)
	return ok1 && ok2 &&
		// path/.. on a different device as path
		(ss1.Dev != ss2.Dev ||
			// path/.. is the same i-node as path - this check is for bind mounts.
			ss1.Ino == ss2.Ino)

            assertTrue(merged.errorPoms().contains(pom2), "Should contain failed POM");
        }

        @Test
        @DisplayName("should handle merging with different POM sets")
        void shouldHandleMergingWithDifferentPOMSets() {
            Path pom1 = Paths.get("pom.xml");
            Path pom2 = Paths.get("module1/pom.xml");
            Path pom3 = Paths.get("module2/pom.xml");

For example:

{* ../../docs_src/metadata/tutorial001_1_py39.py hl[31] *}

## Metadata for tags { #metadata-for-tags }

You can also add additional metadata for the different tags used to group your path operations with the parameter `openapi_tags`.

It takes a list containing one dictionary for each tag.

Each dictionary can contain:

### The Problem { #the-problem }

So, what's the problem with installing packages in the global Python environment?

At some point, you will probably end up writing many different programs that depend on **different packages**. And some of these projects you work on will depend on **different versions** of the same package. 😱

/**
 * A domain name service that resolves IP addresses for host names. Most applications will use the
 * [system DNS service][SYSTEM], which is the default. Some applications may provide their own
 * implementation to use a different DNS server, to prefer IPv6 addresses, to prefer IPv4 addresses,
 * or to force a specific known IP address.
 *
 * Implementations of this interface must be safe for concurrent use.
 */
fun interface Dns {
  /**