anchor.diff:              : TokenType.AMPERSAND_AMPERSAND);
   
       if (_contradictions.isEmpty) {
  -      HashSet<Expression> set = (binaryExpression != null
  +      Set<Expression> set = (binaryExpression != null
             ? _extractComparisons(testingExpression)
             : [testingExpression].toSet())
           ..addAll(truths)
  
positive.code:   }
  }
  
  HashSet<Expression> _extractComparisons(BinaryExpression node) {
    final HashSet<Expression> comparisons = new HashSet<Expression>.identity();
    if (_isComparison(node)) {
      comparisons.add(node);
    }
  
negative.code: import 'package:analyzer/dart/ast/token.dart';
  import 'package:linter/src/util/boolean_expression_utilities.dart';
  
  void _addNodeComparisons(Expression node, Set<Expression> comparisons) {
    if (_isComparison(node)) {
      comparisons.add(node);
    } else if (_isBooleanOperation(node)) {
  