// it in this context.
  virtual AbstractOperation* CreateOperation() = 0;

  // Registers a function with this context, after this the function is
  // available to be called/referenced by its name in this context.
  virtual absl::Status RegisterFunction(AbstractFunction*) = 0;
  // Remove a function. 'func' argument is the name of a previously added
  // FunctionDef. The name is in fdef.signature.name.

// current row and stores the result.
//
// On success, it returns (nil, nil).
func (e *FuncExpr) evalAggregationNode(r Record, tableAlias string) error {
	// It is assumed that this function is called only when
	// `e` is an aggregation function.

	var val *Value
	var err error
	funcName := e.getFunctionName()
	if aggFnCount == funcName {
		if e.Count.StarArg {
			// Handle COUNT(*)

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps

The process normally is that **you define** in your code what is the message that you will send, the **body of the request**.

	Checksum *hash.Checksum
	MD5Hex   string
}

// fanOutPutObject takes an input source reader and fans out multiple PUT operations
// based on the incoming fan-out request, a context cancellation by the caller
// would ensure all fan-out operations are canceled.

In an advanced scenario where you know you need the dependency to be called at every step (possibly multiple times) in the same request instead of using the "cached" value, you can set the parameter `use_cache=False` when using `Depends`:

//// tab | Python 3.8+

```Python hl_lines="1"

## Platform architecture

Gradle is arranged into several coarse-grained components called "platforms".
Each platform provides support for some kind of automation, such as building JVM software or building Gradle plugins.
Most platforms typically build on the features of other platforms.

		// in the beginning of erasure set healing
		if err := bgSeq.healBucket(objAPI, bucket, true); err != nil {
			// Set this such that when we return this function
			// we let the caller retry this disk again for the
			// buckets that failed healing.
			retErr = err
			healingLogIf(ctx, err)
			continue
		}

		var (
			vc   *versioning.Versioning
			lc   *lifecycle.Lifecycle

        }
        tasks.named("publishLocalPublicationToLocalRepository") {
            dependsOn("signGradleDistributionPublication")
        }
    }
}

/**
 * Tasks that are called by the (currently separate) promotion build running on CI.
 */
tasks.register("promotionBuild") {
    description = "Build production distros, smoke test them and publish"
    group = "publishing"

			gotCall <- struct{}{}
			select {
			case <-ctx.Done():
				gotCall <- struct{}{}
			case <-cleanReqs:
				panic("should not be called")
			}
			return nil
		},
		OutCapacity: 1,
		InCapacity:  1,
	}
	errFatal(remote.RegisterSingleHandler(handlerTest, h1))
	errFatal(remote.RegisterStreamingHandler(handlerTest2, h2))

```Python hl_lines="10"
{!> ../../docs_src/dependencies/tutorial011.py!}
```

////

In this case, this `__call__` is what **FastAPI** will use to check for additional parameters and sub-dependencies, and this is what will be called to pass a value to the parameter in your *path operation function* later.

## Parameterize the instance

And now, we can use `__init__` to declare the parameters of the instance that we can use to "parameterize" the dependency: