code: def get_isob_quant_data(pquant, header, fnid, featmap, featcol, qmap):
      
      feat_dbid = featmap[pquant[header[featcol]]]
      for channel_name, (channel_id, psmfield) in qmap[fnid].items():
          if psmfield is None:
              yield (feat_dbid, channel_id, pquant[channel_name])
          else:
              yield (feat_dbid, channel_id, pquant[channel_name],
                     pquant[psmfield])
docs: Turns a dict from a line of protein/peptide quant data into a set of
      tuples that can be stored in db