class RooStats::AsymptoticCalculator: public RooStats::HypoTestCalculatorGeneric

 set print level (static function)
 0 minimal, 1 normal,  2 debug

 constructor for asymptotic calculator from Data set  and ModelConfig
 The constructor will perform a global fit of the model to the data
 and build an Asimov data set.
 It will then also fit the model to the Asimov data set to find the likelihood value
 of the Asimov data set
 NOTE: If a fit has been done before, one for speeding up could set all the initial prameters
 to the fit value and in addition set the null snapshot to the best fit

 It performs an hypothesis tests using the likelihood function
 and computes the p values for the null and the alternate using the asymptotic
 formulae for the profile likelihood ratio.
 See G. Cowan, K. Cranmer, E. Gross and O. Vitells.
 Asymptotic formulae for likelihood- based tests of new physics. Eur. Phys. J., C71:1–19, 2011.
 The formulae are valid only for one POI. If more than one POI exists consider as POI only the
 first one

 function given the null and the alt p value - return the expected one given the N - sigma value

 fill bins by looping recursivly on observables

 iterate a Prod pdf to find the Poisson part to set the observed value to expected one

 set observed value in Poisson to the expected one
 need to iterate on the components of the POisson to get n and nu (nu can be a RooAbsReal)
 (code from G. Petrucciani)

 generate countuing Asimov data for the case when the pdf cannot be extended
 assume pdf is a RooPoisson or can be decomposed in a product of RooPoisson,
 otherwise we cannot know how to make the Asimov data sets in the other cases

 compute the asimov data set for an observable of a pdf
 use the number of bins sets in the observables
 to do :  (possibility to change number of bins)
 impelment integration over bin content

 generate the asimov data for the observables (not the global ones)
 need to deal with the case of a sim pdf

 static function to the an Asimov data set
 given an observed dat set, a model and a snapshot of poi.
 Return the asimov data set + global observables set to values satisfying the constraints

    HypoTestCalculatorGeneric(data, altModel, nullModel, 0)
 {
 }

 get expected limit
      static void GetExpectedLimit(double nsigma, double alpha, double &clsblimit, double &clslimit);

 set using of qtilde, by default is controlled if RoORealVar is limited or not