normalize

# File lib/rexml/parsers/baseparser.rb, line 459
      def normalize( input, entities=nil, entity_filter=nil )
        copy = input.clone
        # Doing it like this rather than in a loop improves the speed
        copy.gsub!( EREFERENCE, '&' )
        entities.each do |key, value|
          copy.gsub!( value, "&#{key};" ) unless entity_filter and
                                      entity_filter.include?(entity)
        end if entities
        copy.gsub!( EREFERENCE, '&' )
        DEFAULT_ENTITIES.each do |key, value|
          copy.gsub!( value[3], value[1] )
        end
        copy
      end