Diagrams of code can be done with UML ¹. A fairly decent ² standard with a set of different diagrams that can be created to visualize code.

In those terms CodeViz will provide a form of simplified class diagrams and a function call mapping?

Will there be sequence diagrams in the future?

¹ https://www.uml.org/ ² It has fallen out of fashion, since many people found it too heavy, and a lot of people have hever heard of it.