|  | class Class { | 
|  | Class call() => this; | 
|  | Class get nonNullableClass => this; | 
|  | NullableIndexClass get nonNullableNullableIndexClass => NullableIndexClass(); | 
|  | int? nullableField; | 
|  | int nonNullableField = 0; | 
|  | int operator [](int key) => key; | 
|  | void operator []=(int key, int value) {} | 
|  | } | 
|  |  | 
|  | class NullableIndexClass { | 
|  | int? operator [](int key) => key; | 
|  | void operator []=(int key, int value) {} | 
|  | } | 
|  |  | 
|  | errors(Class? nullableClass, Class nonNullableClass, int? nullableInt, | 
|  | int nonNullableInt, NullableIndexClass? nullableNullableIndexClass) {} | 
|  | main() {} |