docs: def get_precursors_from_window(quantdb, minmz):
      """Returns a dict of a specified amount of features from the
      ms1 quant database, and the highest mz of those features"""
      featmap = {}
      mz = False
      features = quantdb.get_precursor_quant_window(FEATURE_ALIGN_WINDOW_AMOUNT,
                                                    minmz)
      for feat_id, fn_id, charge, mz, rt in features:
          try:
              featmap[fn_id][charge].append((mz, rt, feat_id))
          except KeyError:
              try:
                  featmap[fn_id][charge] = [(mz, rt, feat_id)]
              except KeyError:
                  featmap[fn_id] = {charge: [(mz, rt, feat_id)]}
      return featmap, mz