How can I know if a non-required RenderSection exists?

@* Omitted code.. *@
@RenderBody()
@RenderSection("Sidebar", required: false)

Is there any way to know in the Omitted code part if the RenderSection Sid开发者_StackOverflowebar exists or not?

@if (IsSectionDefined("Sidebar"))
{
    @RenderSection("Sidebar")
}
else
{
    <div>Some default content</div>
}