code: function () {
          this._files = {};
          this._global = new _File();
          Object.keys(this._data).forEach(function (fileName) {
              var fileCoverage = this._computeFileCoverage(fileName);
              this._files[fileCoverage.name] = fileCoverage;
              this._global.statements.add(fileCoverage.statements);
              this._global.functions.add(fileCoverage.functions);
              this._global.branches.add(fileCoverage.branches);
          }, this);
      }
docs: Compute all coverages