new_contents: def run(diff, col):
      if not len(col):
          return [], []
      last_val = col[0]
      vallist = [last_val]
      rowlist = [0]
      for cur_row, val in enumerate(col[1:], 1):
          if val - last_val != diff:
              vallist.append(val)
              rowlist.append(cur_row)
          last_val = val
      return rowlist, vallist
  
  def enum(col):
      enumlist = sorted(set(col))
      enumdict = dict((val, i) for i, val in enumerate(enumlist))
      newvallist = list(enumdict[val] for val in col)
      return enumlist, newvallist
  
subject: add algorithm functions