# Dependencies - `Depends()` and `Security()`

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

    String stringMethod(String stringParam) {
        'value'
    }

    /**
     * A method that returns void.
     */
    void voidMethod() {
    }

    /**
     * A method that returns a reference type.
     */
    public final CombinedInterface refTypeMethod(JavaInterface someThing, boolean aFlag) {
        null
    }

    /**
     * A method that returns a default type.
     */

     for Merger and v4 Reader and Writers for the Xpp3 XML parser,

   * A {{{../../api/maven-api-toolchain/toolchains.html}Descriptor Reference}}

Extra metadata maintained internally in `xl.meta` for a transitioned object

```
...

	default:
		return nil, errNotImplemented
	}
	return FromTimestamp(t.Add(duration)), nil
}

// dateDiff computes the difference between two times in terms of the
// `timePart` which can be years, months, days, hours, minutes or
// seconds. For difference in years, months or days, the time part,
// including timezone is ignored.
func dateDiff(timePart string, ts1, ts2 time.Time) (*Value, error) {

				"application/xcap-att+xml",
				"application/xcap-caps+xml",
				"application/xcap-el+xml",
				"application/xcap-error+xml",
				"application/xcap-ns+xml",
				"application/xcon-conference-info-diff+xml",
				"application/xcon-conference-info+xml",
				"application/xenc+xml",
				"application/xhtml-voice+xml",
				"application/xml-dtd",
				"application/xml-external-parsed-entity",
				"application/xmpp+xml",

        .isFalse();
    assertEquals(1, Booleans.asList(ARRAY_FALSE_TRUE).lastIndexOf(true));
    List<Boolean> reference = Booleans.asList(ARRAY_FALSE);
    assertEquals(Booleans.asList(ARRAY_FALSE), reference);
    // Explicitly call `equals`; `assertEquals` might return fast
    assertThat(reference.equals(reference)).isTrue();
  }

  public void testAsListHashcode() {
    assertThat(Booleans.asList(EMPTY).hashCode()).isEqualTo(1);

  /*
   * We avoid using a method reference or lambda here for now:
   *
   * - method reference: Inside Google, CacheBuilder is used from the implementation of a custom
   *   ClassLoader that is sometimes used as a system classloader. That's a problem because
   *   method-reference linking tries to look up the system classloader, and it fails because there
   *   isn't one yet.
   *

     for Merger and v4 Reader and Writers for the Xpp3 XML parser,

   * A {{{../../api/maven-api-model/maven.html}Descriptor Reference}}

      <item name="Javadocs" href="apidocs/index.html"/>
      <item name="Source Xref" href="xref/index.html"/>
      <!--item name="FAQ" href="faq.html"/-->
    </menu>
    <menu name="Reference">
      <item name="META-INF/maven/lifecycle.xml" href="lifecycle-mappings.html"/>
      <item name="META-INF/maven/plugin.xml" href="plugin.html"/>
    </menu>
  </body>