# File lib/rqrcode/qrcode/qr_code.rb, line 243
    def is_dark( row, col )
      if !row.between?(0, @module_count - 1) || !col.between?(0, @module_count - 1)
        raise QRCodeRunTimeError, "Invalid row/column pair: #{row}, #{col}"
      end
      @modules[row][col]
    end