## What makes a dependency { #what-makes-a-dependency }

Up to now you have seen dependencies declared as functions.

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

A "**callable**" in Python is anything that Python can "call" like a function.

   * safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * @throws IllegalArgumentException if two keys have the same value or two values have the same
   *     key
   * @throws NullPointerException if any key or value in {@code map} is null
   */
  public static <K, V> ImmutableBiMap<K, V> copyOf(Map<? extends K, ? extends V> map) {

   *
   * @since 8.0
   */
  public static final byte ETX = 3;

  /**
   * End of Transmission: A communication control character used to indicate the conclusion of a
   * transmission, which may have contained one or more texts and any associated headings.
   *
   * @since 8.0
   */
  public static final byte EOT = 4;

  /**

Make sure you evaluate if the **benefits** for your use case compensate the **drawbacks**. 🤓

///

## GraphQL Libraries { #graphql-libraries }

Here are some of the **GraphQL** libraries that have **ASGI** support. You could use them with **FastAPI**:

* <a href="https://strawberry.rocks/" class="external-link" target="_blank">Strawberry</a> 🍓

	if err != nil {
		t.Fatalf("go tool addr2line %v: %v\n%s", os.Args[0], err, string(out))
	}
	f := strings.Split(string(out), "\n")
	if len(f) < 3 && f[2] == "" {
		t.Fatal("addr2line output must have 2 lines")
	}
	funcname = f[0]
	pathAndLineNo := f[1]
	f = strings.Split(pathAndLineNo, ":")
	if runtime.GOOS == "windows" && len(f) == 3 {
		// Reattach drive letter.
		f = []string{f[0] + ":" + f[1], f[2]}
	}

    }

    /**
     * Returns an array that is the concatenation of two arrays.
     * <p>
     * If either or both arrays are {@literal null}, the other array is returned as is.
     * If either or both arrays have a length of {@literal 0}, the other array is returned as is.
     * In any case, the returned array is the same instance as the argument array and is not copied.
     * </p>
     *
     * @param <T>

      headersQueue += headers
    } else {
      check(isLocallyInitiated) { "remotely-initiated streams should have headers" }
    }
  }

  /**
   * Returns true if this stream is open. A stream is open until either:
   *
   *  * A `SYN_RESET` frame abnormally terminates the stream.
   *  * Both input and output streams have transmitted all data and headers.
   *

 *     [chunked][newChunkedSource] or [unknown][newUnknownLengthSource].
 *  6. Read from and close that source.
 *
 * Exchanges that do not have a request body may skip creating and closing the request body.
 * Exchanges that do not have a response body can call
 * [newFixedLengthSource(0)][newFixedLengthSource] and may skip reading and closing that source.
 */
class Http1ExchangeCodec(

## Parameterized dependencies { #parameterized-dependencies }

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.

///

## Lesen Sie zuerst das Tutorial

In den nächsten Abschnitten wird davon ausgegangen, dass Sie das Haupt-[Tutorial – Benutzerhandbuch: Sicherheit](../../tutorial/security/index.md){.internal-link target=_blank} bereits gelesen haben.