def value key, value=nil
      raise "Can not edit attribute #{key} directly. Edit the catalog with 'report.change_catalog(catalog, key, value)'." if ["QSAR_software","QSAR_Algorithm", ""].include? key
      t = @report.at_css key
      t.content = value unless value.nil?
      t.content
    end
def value key, value=nil
      raise "Can not edit attribute #{key} directly. Edit the catalog with 'report.change_catalog(catalog, key, value)'." if ["QSAR_software","QSAR_Algorithm", ""].include? key
      t = @report.at_css key
      t.content = value unless value.nil?
      t.content
    end
Get or Set a value
 e.G.:
@example change the title
  report.value "QSAR_title", "Title of My QSAR"
  #changes the QSAR_title tag to:
  #<QSAR_title chapter="1.1" help="" name="QSAR identifier (title)">Title of My QSAR</QSAR_title>
 @param [String] key Nodename e.g.: "QSAR_title"
 @param [String] value Value to change. If not set the function returns the current value
 @return [Error]  returns Error message if fails
 @return [String] returns value