1. Dart
2. dart:core
3. AssertionError
4. toString method

AssertionError class

1. Constructors
2. AssertionError
3. Properties
4. message
5. hashCode
6. runtimeType
7. stackTrace
8. Methods
9. toString
10. noSuchMethod
11. Operators
12. operator ==

String toString() => "Assertion failed";