void main()
{
    Stream _stream = Stream.fromIterable([1, 2, 3, 4, 5]);
  
    _stream.isEmpty.then((value) => print("isEmpty: $value"));
    _stream.length.then((value) => print("length : $value"));
    _stream.first.then((value) => print("first : $value"));
    _stream.last.then((value) => print("last : $value"));
}

isEmpty: false
first : 1
length : 5
last : 5