class AliAnalysisTaskPidPidCorrelations: public AliAnalysisTaskSE

   , fWriteCorrTree ( kTRUE )
   , fVariablesTreeCorr ( 0x0 )
   , fCorrVariables ( 0 )
   , fFilterBit ( 128 )
   , fHistCorrSingle ( 0x0 )
   , fHistPoolMgrQA ( 0x0 )
   , fHistCorrPairSame ( 0x0 )
   , fHistCorrPairMixed ( 0x0 )
   , fHistConversionbefore ( 0x0 )
   , fHistConversionafter ( 0x0 )
   , fHistPsiMinusPhi ( 0x0 )
   , fHistResonancesBefore ( 0x0 )
   , fHistResonancesRho ( 0x0 )
   , fHistResonancesK0 ( 0x0 )
   , fHistResonancesLambda ( 0x0 )
   , fHistQbefore ( 0x0 )
   , fHistQafter ( 0x0 )
 Dummy constructor ALWAYS needed for I/O.

   , fWriteCorrTree ( kTRUE )
   , fVariablesTreeCorr ( 0x0 )
   , fCorrVariables ( 0 )
   , fFilterBit ( 128 )
   , fHistCorrSingle ( 0x0 )
   , fHistPoolMgrQA ( 0x0 )
   , fHistCorrPairSame ( 0x0 )
   , fHistCorrPairMixed ( 0x0 )
   , fHistConversionbefore ( 0x0 )
   , fHistConversionafter ( 0x0 )
   , fHistPsiMinusPhi ( 0x0 )
   , fHistResonancesBefore ( 0x0 )
   , fHistResonancesRho ( 0x0 )
   , fHistResonancesK0 ( 0x0 )
   , fHistResonancesLambda ( 0x0 )
   , fHistQbefore ( 0x0 )
   , fHistQafter ( 0x0 )
 Constructor

 Destructor. Clean-up the output list, but not the histograms that are put inside
 (the list is owner and will clean-up these histograms). Protect in PROOF case.

 _____ get input event

Write settings to output list

 taken from .../PWGHF/vertexingHF/AliVertexingHFUtils.cxx

_____ number of RECO AOD tracks

_____ number of MC AOD particles

_____ number of RECO AOD tracks

   fList = new THashList;

 takes the binning from <configuration> identified by <tag>
 configuration syntax example:
 eta: 2.4, -2.3, -2.2, -2.1, -2.0, -1.9, -1.8, -1.7, -1.6, -1.5, -1.4, -1.3, -1.2, -1.1, -1.0, -0.9, -0.8, -0.7, -0.6, -0.5, -0.4, -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4
 phi: .....

 returns bin edges which have to be deleted by the caller

 check if the track status flags are set

_____ ITS

___ fills nSigma array with TPC nsigmas for e, mu, pi, K, p

___ fills nSigma array with TOF nsigmas for e, mu, pi, K, p

 check PID signal

 remove particles with the same label

 remove particles Form weak decays
 <tracks> can be the following cases:
 a. tracks: in this case the label is taken and then case b.
 b. particles: it is checked if IsSecondaryFromWeakDecay is true
 <mcObj> can be AOD (TClonesArray) or ESD (AliMCEvent)

   Double_t percentile = fMyAODEvent -> GetCentrality() -> GetCentralityPercentile(fCentralityEstimator.Data());

 calculates dphistar

 calculate inv mass squared
 same can be achieved, but with more computing time with
TLorentzVector photon, p1, p2;
  p1.SetPtEtaPhiM(triggerParticle->Pt(), triggerEta, triggerParticle->Phi(), 0.510e-3);
  p2.SetPtEtaPhiM(particle->Pt(), eta[j], particle->Phi(), 0.510e-3);
  photon = p1+p2;
photon.M()

 calculate inv mass squared approximately

 Determine the number of pools in the pool manager.

 clones a track list by using AliPidPidCorrelationReducedTrack which uses much less memory (used for event mixing)

AliInfo("Terminate","");

 Setters/Getters

   void	SetFilterBit(Int_t fbit)		{ fFilterBit = fbit; }

   void	SetEtaRange(Double_t etaMin, Double_t etaMax) { fTrackEtaMin = etaMin; fTrackEtaMax = etaMax; }

void SetFilterMask(UInt_t i,Int_t iType = 0){fFilterMask = i;fFilterType = iType;}

   Int_t		GetMyFilterBit()		{ return fFilterBit; }
  Double_t* GetNSigmas(AliParticleSpecies species) { return fnsigmas[species]; }	// get nsigma[ipart][idet], calculated in CalculateNSigmas(trk)

  //_______ AliTHn
  AliTHn*	GetHistCorrSingle() {return fHistCorrSingle;}
  void 		SetHistCorrSingle(AliTHn *gHist) { fHistCorrSingle = gHist; }//fHistP->FillParent(); fHistP->DeleteContainers();}
  AliTHn*	GetHistCorrPairSame() {return fHistCorrPairSame;}
  void 		SetHistCorrPairSame(AliTHn *gHist) { fHistCorrPairSame = gHist; }//fHistN->FillParent(); fHistN->DeleteContainers();}
  AliTHn*	GetHistCorrPairMixed() {return fHistCorrPairMixed;}
  void 		SetHistCorrPairMixed(AliTHn *gHist) { fHistCorrPairMixed = gHist; }//fHistN->FillParent(); fHistN->DeleteContainers();}

AliTHn* MakeHistCorr(const Char_t* name) const;