# File lib/spreadsheet/worksheet.rb, line 327
   def format_rectangle(x1, y1, x2, y2, format)
      raise TypeError, "invalid format" unless format.kind_of?(Format)

      x1.upto(x2){ |row|
         y1.upto(y2){ |col|
            write_blank(row, col, format)
         }
      }
   end