# File src/rexml/text.rb, line 225
                def Text::normalize( input, doctype=nil, entity_filter=nil )
                        copy = input.clone
                        # Doing it like this rather than in a loop improves the speed
                        if doctype
                                copy.gsub!( EREFERENCE, '&' )
                                doctype.entities.each_value do |entity|
                                        copy.gsub!( entity.value, 
                                                "&#{entity.name};" ) if entity.value and 
                                                        not( entity_filter and entity_filter.include?(entity) )
                                end
                        else
                                copy.gsub!( EREFERENCE, '&' )
                                DocType::DEFAULT_ENTITIES.each_value do |entity|
                                        copy.gsub!(entity.value, "&#{entity.name};" )
                                end
                        end
                        copy
                end