constructor(
   globalConfig: Config.GlobalConfig,
   options?: CoverageReporterOptions,
 ) {
   super();
   this._coverageMap = istanbulCoverage.createCoverageMap({});
   this._globalConfig = globalConfig;
   this._sourceMapStore = libSourceMaps.createSourceMapStore();
   this._options = options || {};
 }

  createCoverageReport(type: ReportType, data: CoverageMapData | CoverageMap) {
    let map: CoverageMap;

    if (isCoverageMap(data)) {
      map = data;
    } else {
      map = createCoverageMap(data);
    }

    const transformed = this.executor.sourceMapStore.transformCoverage(map);

    const context = createContext({
      dir: this.directory,
      sourceFinder: transformed.sourceFinder,
      watermarks: this.watermarks
    });
    const tree = summarizers.pkg(transformed.map);
    const report = create(type, this.getReporterOptions());
    tree.visit(report, context);
  }

	fnMap: {},
	branchMap: {},
	s: {},
	f: {},
	b: {}
};

const summary1 = createCoverageSummary(summaryData);
summary1.data;
summary1.branches;
summary1.lines;
summary1.functions;
summary1.statements;
const summary2 = createCoverageSummary(summary1);

const map1 = createCoverageMap(coverageMapData);
map1.data;
const map2 = createCoverageMap(map1);
map2.data;

const fileCoverage1 = createFileCoverage('path/to/foo');
fileCoverage1.data;
const fileCoverage2 = createFileCoverage(fileCoverage1.data);
fileCoverage2.data;
const fileCoverage3 = createFileCoverage(fileCoverageData);
fileCoverage3.data;

// CoverageSummary methods and properties
summary1.isEmpty();
summary1.toJSON();
summary1.merge(summary2);