anchor.diff:      'Expression VECTOR Creation': simpleVectorCreation,
       'Binary Op Convenience Creation': convenienceBinaryCreation,
       'Unary Op Convenience Creation': convenienceUnaryCreation,
  +    'Operator simplification': baseOperatorSimplification,
       'Simple REAL evaluation': simpleRealEval,
       'Simple INTERVAL evaluation': simpleIntervalEval,
       'Simple VECTOR evaluation': simpleVectorEval,
       'Default Function Creation': defFuncCreation,
  +    'Default Function simplification': defFuncSimplification,
  +    'Default Function differentiation': defFuncDifferentiation,
       'Default Function REAL evaluation': defFuncRealEval,
       'Default Function INTERVAL evaluation': defFuncIntervalEval,
       'Default Function VECTOR evaluation': defFuncVectorEval,
  
positive.code: 
    void compFunEval() {
      // Evaluate composite functions.
      throw new UnimplementedError();
    }
  
    // TODO test simplify
    // TODO test derive
    void deriveTest() {
      throw new UnimplementedError();
    }
  
    void simplifyTest() {
      throw new UnimplementedError();
    }
  
  
negative.code:     }
    }
    
    /// Test the convenience constructors (unary, auto-wrapping).
    void convenienceUnaryCreation() {
      List<UnaryOperator> unOps = [new UnaryMinus('x')]; 
      
  