Is your feature request related to a problem? Please describe.
Current implementation of FairRunAna::Run() does not match the description.
What we have now in FairRunAna is:

    /**Run from event number NStart to event number NStop */
    void Run(Int_t NStart = 0, Int_t NStop = 0) override;
    /**Run for the given single entry*/
    void Run(Long64_t entry);

Only the first function with NStart < NStop works as described.
The second function is never invoked, i.e. it is impossible to run single event this way.

Unexpected behavior:
Run(-1) - breaks in FairRunInfo::WriteInfo()
Run(0) - runs all input (100 events)
Run(15) - runs first 15 events

Run(-1,any int) - breaks in FairRunInfo::WriteInfo()
Run(15,-1) - runs from event 15 till the end
Run(15,0) - runs first 15 events
Run(15,15) - breaks in FairRunInfo::WriteInfo()
Run(15,16) - runs event number 15

Describe the solution you'd like
Fix the comments to match the behavior.

Change Run(Long64_t entry) to RunSingle(Long64_t entry)

Break properly in FairRunAna::Run() when first int parameter is negative.

Change the behavior of:
Run(15,0) - runs first 15 events
to:
Run(15,0) - run from event 15 till the end

Run(15,15) - breaks in FairRunInfo::WriteInfo()
to
Run(15,15) - run event number 15

Run(15,16) - runs event number 15
to
Run(15,16) - run event 15 and 16

Describe alternatives you've considered
Maybe RunEvent(Long64_t entry) is better than RunSingle(Long64_t entry)?

Maybe we should keep: Run(15,0) - run first 15 events, I really would like to hear your opinion.

Additional context