Let’s jump right in and get a feel for Symex. Open a buffer in your favorite language (ideally, a Lisp!), and, if you prefer, make a copy of it first so that you can make changes without worry. If you are viewing this documentation within Emacs, then keep this window open in a split pane (e.g., via C-x 3) alongside your source buffer so that you can follow along while trying things out.
If your source buffer is not a Lisp, ensure that you are in the Tree-sitter enabled major mode for that language, for instance, python-ts-mode.