J>>class BaseClass
J>>{
J>>    protected virtual async Task<Foo> Bar(int x, Func<Foo, Task<int>> func)
J>>    {        
J>>        ...
J>>        using(var context = new AmbientContext(x))
J>>        {
J>>            var foo = context.Foo;
J>>            var result= await func(foo);
            
J>>            context.Save(smth);
            
J>>            return foo;
J>>        }
J>>    }

J>>