module RubyXL::LegacyCell

def validate_workbook()
  unless workbook.nil? || workbook.worksheets.nil?
    workbook.worksheets.each { |sheet|
      unless sheet.nil? || sheet.sheet_data.nil? || sheet.sheet_data[row].nil?
        if sheet.sheet_data[row][column] == self
          return
        end
      end
    }
  end
  raise "This cell #{self} is not in workbook #{workbook}"
end