anchor.diff:  
     // - - - - - - - - - - - - - - - - - - - - - - - -
     const buildDiffFilenameHandlers = (diffs) => {
  -    // Builds click handlers for all filenames for a given
  -    // [ kata-id, was-index, now-index] tuple.
  +    // Builds filename click handlersfor a [ kata-id, was-index, now-index] tuple.
       const reClicked = (filename) => param.filename === filename;
       const alreadyOpened = [];
   
       const loadFrom = (diff) => {
         const filename = diffFilename(diff);
  -      const sectionCount = diff.section_count;
         let sectionIndex = 0;
  -
         return () => {
           // select line-counts
           $('.diff-line-count').attr('disabled', true);
  
positive.code: 
          // when reclicking a filename then scroll to next diff-chunk.
          // But not when returning to a previously scrolled file.
          if (sectionCount > 0 && (reClicked(filename) || !alreadyOpened.includes(filename))) {
            const $diffSheet = $(`[id="diff_file_content_for_${filename}"]`);
            const section = $(`#${diff.id}_section_${sectionIndex}`);
            const halfSecond = 500;
  
negative.code:             scrollTop: '+=' + (section.offset().top - 250) + 'px'
            }, halfSecond);
            sectionIndex += 1;
            sectionIndex %= diff.section_count;
          }
          param.filename = filename;
          alreadyOpened.push(filename);
  