In this presentation from July 17 2019, Siddhartha Kasivajhula takes us through Symex Mode, which is a way to edit Lisp code in a Vim-like way, as an alternative to packages like paredit and lispy. Symex mode is based on a DSL that can express arbitrary tree navigations, the most common and useful of which are accessible via a modal interface implemented using the excellent Hydra package. Slides for this presentation may be found at https://drive.google.com/file/d/1ectIQAsRR9Gjcki8qc2Q6scqkyp-HYGy/view