code: function nls() {
      const input = event_stream_1.through();
      const output = input.pipe(event_stream_1.through(function (f) {
          if (!f.sourceMap) {
              return this.emit('error', new Error(`File ${f.relative} does not have sourcemaps.`));
          }
          let source = f.sourceMap.sources[0];
          if (!source) {
              return this.emit('error', new Error(`File ${f.relative} does not have a source in the source map.`));
          }
          const root = f.sourceMap.sourceRoot;
          if (root) {
              source = path.join(root, source);
          }
          const typescript = f.sourceMap.sourcesContent[0];
          if (!typescript) {
              return this.emit('error', new Error(`File ${f.relative} does not have the original content in the source map.`));
          }
          nls.patchFiles(f, typescript).forEach(f => this.emit('data', f));
      }));
      return event_stream_1.duplex(input, output);
  }
docs: Returns a stream containing the patched JavaScript and source maps.