class AliSelector: public TSelector

 Constructor. Initialization of pointers

 Destructor

 checks the option string for the debug flag

 The Begin() function is called at the start of the query.
 When running with PROOF Begin() is only called on the client.
 The tree argument is deprecated (on PROOF 0 is passed).

 The SlaveBegin() function is called after the Begin() function.
 When running with PROOF SlaveBegin() is called on each slave server.
 The tree argument is deprecated (on PROOF 0 is passed).

 The Init() function is called when the selector needs to initialize
 a new tree or chain. Typically here the branch addresses of the tree
 will be set. It is normaly not necessary to make changes to the
 generated code, but the routine can be extended by the user if needed.
 Init() will be called many times when running with PROOF.

 The Notify() function is called when a new file is opened. This
 can be either for a new TTree in a TChain or when when a new TTree
 is started when using PROOF. Typically here the branch pointers
 will be retrieved. It is normaly not necessary to make changes
 to the generated code, but the routine can be extended by the
 user if needed.

 The Process() function is called for each entry in the tree (or possibly
 keyed object in the case of PROOF) to be processed. The entry argument
 specifies which entry in the currently loaded tree is to be processed.
 It can be passed to either TTree::GetEntry() or TBranch::GetEntry()
 to read either all or the required parts of the data. When processing
 keyed objects with PROOF, the object is already loaded and is available
 via the fObject pointer.

 This function should contain the "body" of the analysis. It can contain
 simple or elaborate selection criteria, run algorithms on the data
 of the event and typically fill histograms.

 The SlaveTerminate() function is called after all entries or objects
 have been processed. When running with PROOF SlaveTerminate() is called
 on each slave server.

 The Terminate() function is the last function to be called during
 a query. It always runs on the client, it can be used to present
 the results graphically or save the results to file.