How to work with the stack of particles?
	pointer to the stack is returned by AliRun::Stack() or AliRunLoader::Stack()
	total amount of particles in stack for a given event:         AliStack::GetNtrack() or AliRun::GetEvent()
	total amount of primiry particles in stack for a given event: AliStack::GetNprimary() or TreeH()::GetEntries()

How to open session?
                     use static methode  AliRunLoader::Open(


How to retrive hits:
	Hits a stored on primiry by primiry basis. To retrieve all hits one needs to do:
	initialise the root tree and containers:    AliLoader::LoadHits() 
	read number of primiries in current event:
	loop on the list of primiries:



How to retrive sdigits? 
	Sdigits stored in tree S with the branch of TClonesArray, all sdigits in a single TClonesArray
	So the tree has only one entry.
	One needs to say:
	pRich->GetLoader()->LoadSDigits(); this one open file, get the tree and invoke AliRICH::SetTreeAddress()    



gAlice->GetMCApp()->GetCurrentTrackNumber()


What are the debug methodes avail:
	AliModule::GetDebug() 
	AliModule::SetDebug()
	AliRun::GetDebug()
	AliRun::SetDebug()


How to get info for tid number?
	Header and Kinematics trees must be loaded, then possible to retrive pointer to Stack of particles
	Int_t AliRunLoader::LoadHeader(); Int_t AliRunLoader::LoadKinematics()
	AliStack *AliRunLoader::Stack()
	TParticle *AliStack::Particle(tid)
	TParticle::Print()

How to deal with AliRunDigitizer?
	AliRunDigitizer::Exec() just call AliRunDigitizer::Digitize()	

How to avoid using gAlice?
	Rich()->GetLoader()->GetRunLoader()->GetAliRun() returns gAlice global pointer.