anchor.diff:        if (functionBody != null) {
           return BodyInferenceContext.of(functionBody).contextType;
         }
  -//      return _returnType(node);
  -    }
  -    return null;
  -  }
  -
  -  DartType _returnType(AstNode node) {
  -    DartType unwrap(DartType returnType, FunctionBody body) {
  -      if (returnType is InterfaceTypeImpl) {
  -        DartType unwrapAs(ClassElement superclass) {
  -          var convertedType = returnType.asInstanceOf(superclass);
  -          if (convertedType != null) {
  -            return convertedType.typeArguments[0];
  -          }
  -          return null;
  -        }
  -
  -        if (body.isAsynchronous) {
  -          if (body.isGenerator) {
  -            // async* implies Stream<T>
  -            return unwrapAs(typeProvider.streamElement);
  -          } else {
  -            // async implies Future<T>
  -            return unwrapAs(typeProvider.futureElement);
  -          }
  -        } else if (body.isGenerator) {
  -          // sync* implies Iterable<T>
  -          return unwrapAs(typeProvider.iterableElement);
  -        }
  -      }
  -      return returnType;
  -    }
  -
  -    var parent = node.parent;
  -    while (parent != null) {
  -      if (parent is MethodDeclaration) {
  -        return unwrap(parent.declaredElement.returnType, parent.body);
  -      } else if (parent is ConstructorDeclaration) {
  -        return parent.declaredElement.returnType;
  -      } else if (parent is FunctionDeclaration) {
  -        return unwrap(
  -            parent.declaredElement.returnType, parent.functionExpression.body);
  -      }
  -      parent = parent.parent;
       }
       return null;
     }
  
positive.code:       if (functionBody != null) {
          return BodyInferenceContext.of(functionBody).contextType;
        }
  //      return _returnType(node);
      }
      return null;
    }
  
negative.code: import 'package:analyzer/dart/element/type.dart';
  import 'package:analyzer/dart/element/type_provider.dart';
  import 'package:analyzer/dart/element/type_system.dart';
  import 'package:analyzer/src/dart/resolver/body_inference_context.dart';
  
  /// Convert a relevance score (assumed to be between `0.0` and `1.0` inclusive)
  