hunk.code_window: import { Observable } from '../../Observable';
   import { _do, DoSignature } from '../../operator/do';
   Observable.prototype.do = _do;
   declare module '../../Observable' {
     interface Observable<T> {
       do: DoSignature<T>;
  
hunk.labels: keep keep keep add keep keep keep keep
hunk.after_edit: Observable.prototype._do = _do;
  
hunk.file_path: src/add/operator/do.ts
hunk.type: add
file: var welcomeText = (
    ' ____           _ ____      \n'+
    '|  _ \\ __  __  | / ___|    \n'+
    '| |_) |\\ \\/ /  | \\___ \\  \n'+
    '|  _ <  >  < |_| |___) |    \n'+
    '|_| \\_\\/_/\\_\\___/|____/ \n'+
    '\nTry this code to get started experimenting with RxJS:\n'+
    '\n    var subscription = Rx.Observable.interval(500)'+
    '.take(4).subscribe(function (x) { console.log(x) });\n'
  );
  if (console.info) {
    console.info(welcomeText);
  } else {
    console.log(welcomeText);
  }
  