I’m looping over a bunch of entries in a collection of files by adding them to a TChain object. The problem is the TTree object in each file doesn’t always have all of the same branches. Of course, when I call up an entry (using GetEntry), pyROOT throws an AttributeError when I try to do something with a branch that does not exist in that entry. The Draw command works just fine, but I’m trying to do an analysis where I am stepping back and forth over some events (checking for correlations to the previous or next event). The easiest solution is to simply bring up an entry in the TChain, check for the existence of the branch I’m after, and then do my analysis if that branch is there. I’m having a hard time figuring out how to do that existence check though. Does anyone have a suggestion?