StreamCloser<T> constructor Null safety

1. Flutter
2. async
3. StreamCloser<T>
4. StreamCloser constructor

StreamCloser class

1. Constructors
2. StreamCloser
3. Properties
4. hashCode
5. isClosed
6. runtimeType
7. Methods
8. bind
9. cast
10. close
11. noSuchMethod
12. toString
13. Operators
14. operator ==