I tried running a test PAT-tuple, and I am getting an error here. With `python -i`, I get
```
File "/afs/hep.wisc.edu/cms/belknap/fsa539/python/FinalStateAnalysis/PatTools/patFinalStateProducers.py", line 227, in produce_final_states
    if n_jets>0 and not (n_jets==2 and n_muons==1):
UnboundLocalError: local variable 'n_jets' referenced before assignment
```