message: docs(operators): emiited to emitted
  spell mistake.
diff: @@ -9,7 +9,7 @@ import { Observer, MonoTypeOperatorFunction, TeardownLogic } from '../types';
  * Returns an Observable that emits the single item emitted by the source Observable that matches a specified
  * predicate, if that Observable emits one such item. If the source Observable emits more than one such item or no
  * items, notify of an IllegalArgumentException or NoSuchElementException respectively. If the source Observable
  - * emits items but none match the specified predicate then `undefined` is emiited.
  + * emits items but none match the specified predicate then `undefined` is emitted.
  *
  * ![](single.png)
  *
  