tmux is UTF-8, so if $TMUX is set (tmux running in tmux), the client is UTF-8. Also try to make the existing checks more readable.
tmux is UTF-8, so if $TMUX is set (tmux running in tmux), the client is
UTF-8. Also try to make the existing checks more readable.

klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux