nsIRDFDataSource* datasource = (nsIRDFDataSource*) mDataSources[m];
CompositeDataSourceImpl::HasAssertionN(int n,                                       nsIRDFResource* aSource,                                       nsIRDFResource* aProperty,                                       nsIRDFNode* aTarget,                                       PRBool aTruthValue){    nsresult rv;    for (PRInt32 m = 0; m < n; ++m) {        nsIRDFDataSource* datasource = (nsIRDFDataSource*) mDataSources[m];        PRBool result;        rv = datasource->HasAssertion(aSource, aProperty, aTarget, aTruthValue, &result);        if (NS_FAILED(rv))            return PR_FALSE;        // found it!        if (result)            return PR_TRUE;    }    return PR_FALSE;}