code: function find$2(predicate, thisArg) {
      if (typeof predicate !== 'function') {
          throw new TypeError('predicate is not a function');
      }
      return this.lift(new FindValueOperator(predicate, this, false, thisArg));
  }
docs: /* tslint:disable:max-line-length 
  Emits only the first value emitted by the source Observable that meets some
  condition.
  
  <span class="informal">Finds the first value that passes some test and emits
  that.</span>
  
  <img src="./img/find.png" width="100%">
  
  `find` searches for the first item in the source Observable that matches the
  specified condition embodied by the `predicate`, and returns the first
  occurrence in the source. Unlike {@link first}, the `predicate` is required
  in `find`, and does not emit an error if a valid value is not found.
  
  @example <caption>Find and emit the first click that happens on a DIV element</caption>
  var clicks = Rx.Observable.fromEvent(document, 'click');
  var result = clicks.find(ev => ev.target.tagName === 'DIV');
  result.subscribe(x => console.log(x));
  
  @see {@link filter}
  @see {@link first}
  @see {@link findIndex}
  @see {@link take}
  
  @param {function(value: T, index: number, source: Observable<T>): boolean} predicate
  A function called with each item to test for condition matching.
  @param {any} [thisArg] An optional argument to determine the value of `this`
  in the `predicate` function.
  @return {Observable<T>} An Observable of the first item that matches the
  condition.
  @method find
  @owner Observable