def contains_row? row
      raise ArgumentError, "table should be a Workbook::Row (you passed a #{t.class})" unless row.is_a?(Workbook::Row)
      self.collect{|r| r.object_id}.include? row.object_id
    end
def contains_row? row
      raise ArgumentError, "table should be a Workbook::Row (you passed a #{t.class})" unless row.is_a?(Workbook::Row)
      self.collect{|r| r.object_id}.include? row.object_id
    end
Returns true if the row exists in this table

 @param [Workbook::Row] row to test for
 @return [Boolean] whether the row exist in this table