anchor.diff:  
   import 'package:analyzer/context/declared_variables.dart';
   import 'package:analyzer/dart/ast/ast.dart';
  +import 'package:analyzer/dart/ast/visitor.dart';
   import 'package:analyzer/dart/element/element.dart';
   import 'package:analyzer/error/error.dart';
   import 'package:analyzer/error/listener.dart';
   import 'package:analyzer/src/context/context.dart';
   import 'package:analyzer/src/dart/analysis/file_state.dart';
   import 'package:analyzer/src/dart/ast/ast.dart';
  +import 'package:analyzer/src/dart/ast/utilities.dart';
   import 'package:analyzer/src/dart/constant/evaluation.dart';
   import 'package:analyzer/src/dart/constant/utilities.dart';
   import 'package:analyzer/src/error/codes.dart';
  
positive.code:           new UnusedLocalElementsVerifier(errorListener, usedElements);
        unit.element.accept(visitor);
      }
    }
  
    void _computePendingMissingRequiredParameters(
  
negative.code:           _computeHints(file, unit);
          });
        }
  
        if (_analysisOptions.lint) {
          units.forEach((file, unit) {
            _computeLints(file, unit);
          });
        }
      } finally {
        _context.dispose();
      }
  