text: A = [9,4,7,2,19,3,12, 3, 17, 9, 23, 7, 52]
  B = [7, 3, 9]
  
  def find_sublist(universe, uniques):
      recents =  {val: False for val in uniques}
      ll_order = {val:(None, None) for val in uniques}
      head, tail = None, None
      count_identified = 0
      cur_leftmost = 0
      lowest_length = len(universe)
      for i, item in enumerate(universe):
          if not(item in recents):
              continue
          if recents[item] is False:
              count_identified += 1
              if head is None:
                  head = item
          else:
  
          recents[item]= i
          if not count_identified==len(uniques):
              continue
          cur_length = i - recents[head]
          if cur_length < lowest_length:
              print 'reassigning to: {}->{}'.format(i,recents[head])
              lowest_length = cur_length
      return lowest_length if count_identified==len(uniques) else None
  
  print find_sublist(A, B)
  