/// <summary>Assert / add a new triple for this graph</summary>
public Graph Assert(Node <UriOrBlank> subject, UriNode predicate, Node @object, out Quad quad)
{
_rdf.Assert(Id, subject, predicate, @object, out quad);
return(this);
}
/// <summary>Assert / add a quad.</summary>
public static IRdfData Assert(this IRdfData rdf, Node <UriOrBlank> graph,
Node <UriOrBlank> sub,
UriNode predicate, Node val)
=> rdf.Assert(graph, sub, predicate, val, out _);