-Supported fields are: date, count, authors, subject, tags.
-For example:
- (setq notmuch-search-result-format
- \\='((\"authors\" . \"%-40s\")
- (\"subject\" . \"%s\")))
+List of pairs of (field . format-string). Supported field
+strings are: \"date\", \"count\", \"authors\", \"subject\",
+\"tags\". It is also supported to pass a function in place of a
+field name. In this case the function is passed the thread
+object (plist) and format string.