As any unix aficionado, I have my own stash of custom commands. At some point in time, I mimicked Pedro Melo’s idea of starting all of them with an underscore, to have a more precise auto-complete.
Fast-forward some years, and in my macOS and ubuntu shell, I have plenty of system scripts that start with one or two underscores, undermining the autocomplete advantage.
Brandon Rhodes proposes to use the comma. Personally, I am not a fan of having a punctuation symbol that has other meaning in programming languages inside a shell that parses input as a programming language (zsh these days). But this is the type of yak shaving that automates your workflows.