## Return Type and Data Filtering

Let's continue from the previous example. We wanted to **annotate the function with one type**, but we wanted to be able to return from the function something that actually includes **more data**.

We want FastAPI to keep **filtering** the data using the response model. So that even though the function returns more data, the response will only include the fields declared in the response model.

// 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(*)
			e.aggregate.runningCount++

// once (i.e., on the main function side) in running distributed functions.
// This test creates a cluster with two workers, create a variable on the
// second worker, and run a distributed function (VariableAddFunction) whose ops
// span the local and remote workers. If the graph optimization pass is executed
// on both the main function side and the component function side, an error will

  return grads;
}

std::vector<string> GetFuncNames(const tensorflow::GraphDef& graph_def) {
  std::vector<string> names;
  auto functions = graph_def.library().function();
  names.reserve(functions.size());
  for (const tensorflow::FunctionDef& func : functions) {
    names.push_back(func.signature().name());
  }
  std::sort(names.begin(), names.end());
  return names;
}

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.collect.testing.IteratorTester;
import com.google.common.collect.testing.ListTestSuiteBuilder;
import com.google.common.collect.testing.TestStringListGenerator;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.collect.testing.IteratorTester;
import com.google.common.collect.testing.ListTestSuiteBuilder;
import com.google.common.collect.testing.TestStringListGenerator;

	case e.DateDiff != nil:
		return sqlFnDateDiff
	default:
		return ""
	}
}

// evalSQLFnNode assumes that the FuncExpr is not an aggregation
// function.
func (e *FuncExpr) evalSQLFnNode(r Record, tableAlias string) (res *Value, err error) {
	// Handle functions that have phrase arguments
	switch e.getFunctionName() {
	case sqlFnCast:
		expr := e.Cast.Expr
		res, err = expr.castTo(r, strings.ToUpper(e.Cast.CastType), tableAlias)

          Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    throw new UnsupportedOperationException();
  }

  /**
   * Not supported. This method does not make sense for {@code BiMap}. This method exists only to
   * hide {@link ImmutableMap#toImmutableMap(Function, Function, BinaryOperator)} from consumers of

    (For example, a function in a library to compute square roots has
    a purpose that is entirely well-defined independent of the
    application.  Therefore, Subsection 2d requires that any
    application-supplied function or table used by this function must
    be optional: if the application does not supply it, the square
    root function must still compute square roots.)

   * {@link java.util.stream.Collectors#toMap(java.util.function.Function,
   * java.util.function.Function) Collectors.toMap(Function, Function)}, which throws an {@code
   * IllegalStateException}.)
   *
   * @since 21.0
   */
  public static <T extends @Nullable Object, K extends Enum<K>, V>
      Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
          java.util.function.Function<? super T, ? extends K> keyFunction,