message: Update understanding-session.md
diff: @@ -37,7 +37,7 @@ What if we need more stuff in network session;
  }
  const MyModule = new GraphQLModule({
  context(session: MyModuleSession) {
  - res.on('finish', () => {
  + session.res.on('finish', () => {
  // Some cleanup
  });
  return {
  