docs: def dict_diff(dicts):
      """
      Subset dictionaries to keys which map to multiple values
      """
      diff_keys = set()
  
      for k in union(set(d.keys()) for d in dicts):
          values = []
          for d in dicts:
              if k not in d:
                  diff_keys.add(k)
                  break
              else:
                  values.append(d[k])
                  if nunique(values) > 1:
                      diff_keys.add(k)
                      break
  
      return [dict_subset(d, diff_keys) for d in dicts]