code: def _add_uniq_value_to_dict_bf(d, k, v):
      
      prev = d.get(k)
      if prev is None:
          d[k] = v
      elif isinstance(prev, list):
          if not isinstance(v, list):
              v = [v]
          for sel in v:
              found = False
              for el in prev:
                  if el == sel:
                      found = True
                      break
              if not found:
                  prev.append(sel)
      else:
          if isinstance(v, list):
              prev = [prev]
              for sel in v:
                  found = False
                  for el in prev:
                      if el == sel:
                          found = True
                          break
                  if not found:
                      prev.append(sel)
              if len(prev) > 1:
                  d[k] = prev
          elif prev != v:
              d[k] = [prev, v]
docs: Like _add_value_to_dict_bf but will not add v if another
      element in under key `k` has the same value.