1. Dart
2. dart:html
3. UnderlyingSourceBase
4. cancel method

UnderlyingSourceBase class

1. Properties
2. hashCode
3. runtimeType
4. Methods
5. cancel
6. notifyLockAcquired
7. notifyLockReleased
8. pull
9. start
10. noSuchMethod
11. toString
12. Operators
13. operator ==

Future cancel(Object reason) =>
    promiseToFuture(JS("", "#.cancel(#)", this, reason));