<ExtensionAttribute()>
Public Overloads Shared Function All( _
   ByVal source As IEntityScalarQuery, _
   ByVal predicateDescription As IPredicateDescription, _
   Optional ByVal userCallback As Action(Of EntityScalarQueryOperation(Of Boolean)), _
   Optional ByVal userState As Object _
) As EntityScalarQueryOperation(Of Boolean)

Dim source As IEntityScalarQuery
Dim predicateDescription As IPredicateDescription
Dim userCallback As Action(Of EntityScalarQueryOperation(Of Boolean))
Dim userState As Object
Dim value As EntityScalarQueryOperation(Of Boolean)
 
value = EntityScalarAsyncExtensions.All(source, predicateDescription, userCallback, userState)

[ExtensionAttribute()]
public static EntityScalarQueryOperation<bool> All( 
   IEntityScalarQuery source,
   IPredicateDescription predicateDescription,
   Action<EntityScalarQueryOperation<bool>> userCallback,
   object userState
)

[ExtensionAttribute()]
public:
static EntityScalarQueryOperation<bool>^ All( 
   IEntityScalarQuery^ source,
   IPredicateDescription^ predicateDescription,
   Action<EntityScalarQueryOperation<bool>^>^ userCallback,
   Object^ userState
) 

public void AsyncAllWithPredicate() {
  var op = _entityManager.Employees.AsScalarAsync().All(e => e.Country == "Brazil");
  op.Completed += (o, e) => {
    bool result = e.Result;
  };
}