model property Null safety

1. jrpn
2. jrpn15.model15c
3. Memory15<OT extends ProgramOperation>
4. model property

Memory15 class

1. Constructors
2. Memory15
3. Properties
4. availableRegisters
5. hashCode
6. model
7. numRegisters
8. policy
9. program
10. programNybbles
11. registers
12. runtimeType
13. storage
14. totalNybbles
15. Methods
16. availableRegistersWithProgram
17. decodeJson
18. initializeSystem
19. noSuchMethod
20. reset
21. toJson
22. toString
23. Operators
24. operator ==