code: def dense_rank(expr, sort=None, ascending=True):
      
      return _rank_op(expr, DenseRank, types.int64, sort=sort, ascending=ascending)
docs: Calculate dense rank of a sequence expression.
  
      :param expr: expression for calculation
      :param sort: name of the sort column
      :param ascending: whether to sort in ascending order
      :return: calculated column