One good idea for Mathcad Express

Mathcad Express is Mathcad Prime without some function.

Intercept and slope functions are closed in Mathcad Express for example.

But we can create its in Mathcad Prime and use in Mathcad Express - see the picture and attach.

Can you create others closed function for Express?

PS - last and rows function and a sum operator are open in Express? Check some body please!