message: docs(operators): variable interval rename to i
  * docs(operators): variable interval rename to i
  in example the const interval(1000); will result in error. so rename interval to i
  * docs(takeUntil): Changed `i` to `source`.
  `i` is usually for indices and integers.
diff: @@ -26,9 +26,9 @@ import { MonoTypeOperatorFunction, TeardownLogic } from '../types';
  * ## Example
  * Tick every second until the first click happens
  * ```javascript
  - * const interval = interval(1000);
  + * const source = interval(1000);
  * const clicks = fromEvent(document, 'click');
  - * const result = interval.pipe(takeUntil(clicks));
  + * const result = source.pipe(takeUntil(clicks));
  * result.subscribe(x => console.log(x));
  * ```
  *
  