code: def abfGroupFiles(groups,folder):
      
      assert os.path.exists(folder)
      files=os.listdir(folder)
      group2={}
      for parent in groups.keys():
          if not parent in group2.keys():
              group2[parent]=[]
          for ID in groups[parent]:
              for fname in [x.lower() for x in files if ID in x.lower()]:
                  group2[parent].extend([fname])
      return group2
docs: when given a dictionary where every key contains a list of IDs, replace
      the keys with the list of files matching those IDs. This is how you get a
      list of files belonging to each child for each parent.