code: function (content) {
  
              // XXX extension-specific for get blocks too.
              //
              // Eg. for each predefined extensions directives may vary. eg <!--
              // directive --> for html, /** directive **/ for css
              var blocks = getBlocks(content);
  
              content = updateReferences(blocks, content);
  
              compactContent(blocks);
  
              return content;
          }
docs: useref:pre:* are used to preprocess files with the blocks and directives before going through the global replace