(defsubst nnmaildir--mark-to-flag (mark)
"Find the Maildir flag that corresponds to MARK (an atom).
-Return a character, or `nil' if not found.
+Return a character, or nil if not found.
See `nnmaildir-flag-mark-mapping'."
(car (rassq mark nnmaildir-flag-mark-mapping)))
(defsubst nnmaildir--flag-to-mark (flag)
"Find the Gnus mark that corresponds to FLAG (a character).
-Return an atom, or `nil' if not found.
+Return an atom, or nil if not found.
See `nnmaildir-flag-mark-mapping'."
(cdr (assq flag nnmaildir-flag-mark-mapping)))