plementation can still be obtained
through the <tt>RooTreeDataStore::tree()</tt> method. (A pointer to the datastore
can be obtained through the <tt>RooAbsData::store()</tt> method.)
Note that in future releases it is no longer guaranteed that all datasets are implemented
with a plain <tt>TTree</tt> implementation, so any user code that uses the tree
implementation directly should implement checks that the implementation
is indeed tree-based (<tt>data->store()->InheritsFrom(RooTreeDataStore::Class())==true)