anchor.diff:       super.visitVariableDeclaration(vd);
        
        if (!elementAnalysis.containsElement(vd))
  -       engine.errors.addError(new EngineError("A VariableDeclaration was visited, but didn't have a associated elemenet.", source.source, vd.offset, vd.length ), true);
  +       engine.errors.addError(new EngineError("A VariableDeclaration was visited, but didnt have a associated elemenet.", source.source, vd.offset, vd.length ), true);
        
        Element element = elementAnalysis.elements[vd];
        if (element is FieldElement){
  
positive.code:   visitIntegerLiteral(IntegerLiteral n) {
      super.visitIntegerLiteral(n);
      // {int} \in [n]
      types.put(n, _getAbstractType(new Name('int'), constraintAnalysis.dartCore, source));
    }
    
    visitDoubleLiteral(DoubleLiteral n) {
  
negative.code:     
      // exp1 op exp2
      TypeIdentifier leftIdent = new ExpressionTypeIdentifier(be.leftOperand);
      TypeIdentifier rightIdent = new ExpressionTypeIdentifier(be.rightOperand);
      TypeIdentifier nodeIdent = new ExpressionTypeIdentifier(be);
      
      if (be.operator.type == TokenType.AMPERSAND_AMPERSAND ||
          be.operator.type == TokenType.BAR_BAR) {
        // Binop only implemented for bools
        types.put(leftIdent, _getAbstractType(new Name("bool"), constraintAnalysis.dartCore, source));
        types.put(rightIdent, _getAbstractType(new Name("bool"), constraintAnalysis.dartCore, source));
        types.put(nodeIdent, _getAbstractType(new Name("bool"), constraintAnalysis.dartCore, source));
          
      } else {
        //  Binop handled as method call
        //  \forall \gamma \in [exp1], 
        //  \forall (\alpha -> \beta) \in [ \gamma .op ] => 
        //      \alpha \in [exp2] && \beta \in [exp1 op exp2].
        foreach(leftIdent).update((AbstractType gamma) {
          TypeIdentifier methodIdent = new PropertyTypeIdentifier(gamma, new Name.FromToken(be.operator));
          _methodCall(methodIdent, <Expression>[be.rightOperand], nodeIdent);
        });
      }
    }
    
    visitIsExpression(IsExpression n){
  