docs: function expand$2(project, concurrent, scheduler) {
      if (concurrent === void 0) { concurrent = Number.POSITIVE_INFINITY; }
      if (scheduler === void 0) { scheduler = undefined; }
      concurrent = (concurrent || 0) < 1 ? Number.POSITIVE_INFINITY : concurrent;
      return this.lift(new ExpandOperator(project, concurrent, scheduler));
  }