Reweighting multiple histograms quickly

Hello ROOTers
What would be the fastest way to reweight all the histograms in a file? I’m guessing a nested for loop to go over each histogram and then each bin?
The reweighting value is the same for each bin/hist. How do I loop over each histogram without having to call each distinct name? There are about 200 histograms in the file.



this might help: ROOT: tutorials/io/loopdir.C File Reference