scikit-hep
TTree/RNTuple attribute to keep track of the loaded branches
In Coffea, we would like a TTree/RNTuple attribute to keep track of the loaded branches similar to how we can track the number of requested bytes from a file: https://github.com/scikit-hep/uproot5/blob/b684d675908135d31d7e02405684cb09a4939c6e/src/uproot/source/chunk.py#L45-L54
This branch deserialization log should contain duplicates (i.e. if a branch is deserialized twice, it should be added twice to the log) and the log should be ordered in the way the branches were deserialized in time. However, I don't think it should contain duplicates if the branch was taken from the uproot cache. Overall, I think it should contain all the branches that uproot actually spent time deserializing in order. The simplest thing would be a list of strings I believe or you can make it a more complicated object to keep track of the number of bytes for example of each deserialization and other extra info you may want.
cc @pfackeldey @lgray
