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: 
  import { Observable } from '../../Observable';
  import { _do, DoSignature } from '../../operator/do';
  
  Observable.prototype.do = _do;
  
  declare module '../../Observable' {
    interface Observable<T> {
      do: DoSignature<T>;
    }
  }