anchor.diff:    
     ExpressionTypeIdentifier(Expression this.exp);
     
  -  int get hashCode => exp.hashCode; 
  +  int get hashCode => exp.hashCode;
   }
   
   
  
positive.code: class NominalType extends AbstractType {
    
    ClassElement element;
    ConstraintAnalysis constraintAnalysis;
      
    
    NominalType(ClassElement this.element, ConstraintAnalysis this.constraintAnalysis);
   
    
    String toString() => element.name.toString();
  
negative.code:   AbstractType typeClassElement(ClassElement element){
      if (types.containsKey(element.ast))
        return types[element.ast];
      return types[element.ast] = new NominalType(element);
    }
    
    AbstractType resolveType(TypeName type, LibraryElement library, SourceElement source){
      return new NominalType(elementAnalysis.resolveClassElement(type.name.toString(), library, source));
    }
    
    ParameterTypes resolveParameters(FormalParameterList paramList, LibraryElement library, SourceElement source){
  