library test /*isNonNullableByDefault*/;
import self as self;
import "dart:async" as asy;
import "dart:core" as core;

import "dart:async";

static method main() → dynamic async /* futureValueType= dynamic */ {
  () → asy::Stream<Null> f = () → asy::Stream<Null> async* {
    yield null;
  };
  asy::Stream<dynamic> y = f(){() → asy::Stream<Null>};
  asy::Stream<core::String?> z = f(){() → asy::Stream<Null>};
  core::String? s = await f(){() → asy::Stream<Null>}.{asy::Stream::first}{asy::Future<Null>};
}