# 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()`

			targetIDs = targetIDs.Union(targetIDSet)
		}
	}

	return targetIDs
}

// Clone - returns copy of this rules.
func (rules Rules) Clone() Rules {
	rulesCopy := make(Rules)

	for pattern, targetIDSet := range rules {
		rulesCopy[pattern] = targetIDSet.Clone()
	}

	return rulesCopy
}

// Union - returns union with given rules as new rules.

		return bts, nil
	}
	var zb0002 uint32
	zb0002, bts, err = msgp.ReadMapHeaderBytes(bts)
	if err != nil {
		err = msgp.WrapError(err, "Values")
		return o, err
	}
	dst := *m
	if dst == nil {
		dst = make(map[string]string, zb0002)
	} else if len(dst) > 0 {
		for key := range dst {
			delete(dst, key)
		}
	}
	for zb0002 > 0 {
		var za0001 string
		var za0002 string
		zb0002--

errors.invalid_query_cannot_process=Kan de opgegeven query niet verwerken.
errors.crud_invalid_mode = Ongeldige modus. (Is {1}, niet {0})
errors.crud_failed_to_create_instance = Kan geen nieuwe gegevens maken.
errors.crud_failed_to_create_crud_table = Kan geen nieuwe gegevens maken. ({0})
errors.crud_failed_to_update_crud_table=Kan gegevens niet bijwerken. ({0})
errors.crud_failed_to_delete_crud_table=Kan gegevens niet verwijderen. ({0})

```python
from fastapi import WebSocket
```

/// tip

When you want to define dependencies that should be compatible with both HTTP and WebSockets, you can define a parameter that takes an `HTTPConnection` instead of a `Request` or a `WebSocket`.

///

::: fastapi.WebSocket
    options:
        members:
            - scope
            - app
            - url
            - base_url

    assertTrue(iter.hasNext());
    assertTrue(iter.hasNext());
    assertTrue(iter.hasNext());
    assertEquals(1, (int) iter.next());

    assertFalse(iter.hasNext());

    // Make sure computeNext() doesn't get invoked again
    assertFalse(iter.hasNext());

    assertThrows(NoSuchElementException.class, iter::next);
  }

  public void testDefaultBehaviorOfPeek() {
    /*

## Managing hermetic Python

To make sure that TensorFlow's build is reproducible, behaves uniformly across
supported platforms (Linux, Windows, MacOS) and is properly isolated from
specifics of a local system, we rely on hermetic Python (see
[rules_python](https://github.com/bazelbuild/rules_python)) for all build
and test commands executed via Bazel. This means that your system Python
installation will be ignored during the build and Python interpreter itself

	saver := z.serverPools[o.pool].sets[o.set]

	// Disconnect from call above, but cancel on exit.
	listCtx, cancel := context.WithCancel(GlobalContext)
	saveCh := make(chan metaCacheEntry, metacacheBlockSize)
	inCh := make(chan metaCacheEntry, metacacheBlockSize)
	outCh := make(chan metaCacheEntry, o.Limit)

	filteredResults := o.gatherResults(ctx, outCh)

	mc := o.newMetacache()

		beginningOfLine: true,
		macros:          predefine(flags.D),
	}
}

// predefine installs the macros set by the -D flag on the command line.
func predefine(defines flags.MultiFlag) map[string]*Macro {
	macros := make(map[string]*Macro)
	for _, name := range defines {
		value := "1"
		i := strings.IndexRune(name, '=')
		if i > 0 {
			name, value = name[:i], name[i+1:]
		}
		tokens := Tokenize(name)

	subStateless map[subHandlerID]*StatelessHandler
	subStreams   map[subHandlerID]*StreamHandler
}

func (h *handlers) init() {
	h.subSingle = make(map[subHandlerID]SingleHandlerFn)
	h.subStateless = make(map[subHandlerID]*StatelessHandler)
	h.subStreams = make(map[subHandlerID]*StreamHandler)
}

func (h *handlers) hasAny(id HandlerID) bool {
	if !id.valid() {
		return false
	}