anchor.diff:    _NullabilityNodeImmutable(this._debugPrefix, this.isNullable) : super._();
   
     @override
  -  bool get hasNonNullIntent => !isNullable;
  +  _NullabilityState get _state => isNullable
  +      ? _NullabilityState.ordinaryNullable
  +      : _NullabilityState.nonNullable;
   }
   
   class _NullabilityNodeSimple extends NullabilityNodeMutable {
  
positive.code:   bool get isPossiblyOptional => _isPossiblyOptional;
  
    String get _debugPrefix;
  
    /// Records the fact that an invocation was made to a function with named
    /// parameters, and the named parameter associated with this node was not
  
negative.code:         var suffix = suffixes.isNotEmpty ? ' (${suffixes.join(', ')})' : '';
          return '${edge.destinationNode}$suffix';
        });
        var state = source._state;
        print('$source ($state) -> ${destinations.join(', ')}');
      }
    }
  
  