NS_ASSERTION(observer != nsnull, "null ptr"); if (! observer)
NS_PRECONDITION(aObserver != nsnull, "null ptr"); if (! aObserver)
InMemoryDataSource::AddObserver(nsIRDFObserver* observer){    NS_ASSERTION(observer != nsnull, "null ptr");    if (! observer)        return NS_ERROR_NULL_POINTER;    NS_AUTOLOCK(mLock);    if (! mObservers) {        nsresult rv;        rv = NS_NewISupportsArray(getter_AddRefs(mObservers));        if (NS_FAILED(rv)) return rv;    }    mObservers->AppendElement(observer);    return NS_OK;}