Observer::OnUnassert(nsIRDFResource* aSource,
Observer::OnUnassert(nsIRDFDataSource* aDataSource, nsIRDFResource* aSource,
Observer::OnUnassert(nsIRDFResource* aSource,                     nsIRDFResource* aProperty,                     nsIRDFNode* aTarget){    return rdf_WriteOp("unassert", aSource, aProperty, aTarget);}