I've looked at this similar question which asks about creating a tmux session, or attaching if it doesn't exist.
What I'd like to do is a little different: create a tmux session if it doesn't exist, but don't attach. The plan is to create a few different sessions with canonical names, then send commands to them using tmux send. Is there an easy way in tmux or shell scripting to create a session with a specific name only if it doesn't exist?