code: function writeReport(fileResult, formatter, formattedSourceLines, baseDir) {
      var fileName = fileResult.fileName,
          stats = StatUtils.decorateStatPercentages(fileResult.stats),
          parentDir = path.normalize(baseDir + '/..'),
          mutations = formatter.formatMutations(fileResult.mutationResults),
          breadcrumb = new IndexHtmlBuilder(baseDir).linkPathItems({
              currentDir: parentDir,
              fileName: baseDir + '/' + fileName + '.html',
              separator: ' >> ',
              relativePath: getRelativeDistance(baseDir + '/' + fileName, baseDir ),
              linkDirectoryOnly: true
          });
  
      var file = Templates.fileTemplate({
          sourceLines: formattedSourceLines,
          mutations: mutations
      });
  
      fs.writeFileSync(
          path.join(baseDir, fileName + ".html"),
          Templates.baseTemplate({
              style: Templates.baseStyleTemplate({ additionalStyle: Templates.fileStyleCode }),
              script: Templates.baseScriptTemplate({ additionalScript: Templates.fileScriptCode }),
              fileName: path.basename(fileName),
              stats: stats,
              status: stats.successRate > this._config.successThreshold ? 'killed' : stats.all > 0 ? 'survived' : 'neutral',
              breadcrumb: breadcrumb,
              generatedAt: new Date().toLocaleString(),
              content: file
          })
      );
  }
docs: write the report to file