Within _make_tuples functions, it may be possible to automate query formation for fetching data that can be uniquely identified by its attribute name.

For example,

nslices = (preprocess.Prepare.Galvo() & key).fetch1['nslices'] 
traces  = (preprocess.ExractTraces.Traces() & key).fetch['trace']  

would be replaced with

nslices, traces = dj.get('nslices', 'traces')

This is intended to work from _make_tuples only since it will need to know its place in the data hierarchy and the value of key.